A conserved role of a DEAD box helicase in mRNA masking.

Clam p82 is a member of the cytoplasmic polyadenylation element-binding protein (CPEB) family of RNA-binding proteins and serves dual functions in regulating gene expression in early development. In the oocyte, p82/CPEB is a translational repressor, whereas in the activated egg, it acts as a polyadenylation factor. Coimmunoprecipitations were performed with p82 antibodies in clam oocyte and egg lysates to identify stage-regulated accessory factors. p47 coprecipitates with p82 from oocyte lysates in an RNA-dependent manner and is absent from egg lysate p92-bound material. Clam p47 is a member of the RCK/p54 family of DEAD box RNA helicases. Xp54, the Xenopus homolog, with bona fide helicase activity, is an abundant and integral component of stored mRNP in oocytes (Ladomery et al., 1997). In oocytes, clam p47 and p82/CPEB are found in large cytoplasmic mRNP complexes. Whereas the helicase level is constant during embryogenesis, in contrast to CPEB, clam p47 translocates to nuclei at the two-cell stage. To address the role of this class of helicase in masking, Xp54 was tethered via 3' UTR MS2-binding sites to firefly luciferase, following microinjection of fusion protein and nonadenylated reporter mRNAs into Xenopus oocytes. Tethered helicase repressed luciferase translation three- to fivefold and, strikingly, mutations in two helicase motifs (DEAD--> DQAD and HRIGR-->HRIGQ), activated translation three- to fourfold, relative to MS2. These data suggest that this helicase family represses translation of maternal mRNA in early development, and that its activity may be attenuated during meiotic maturation, prior to cytoplasmic polyadenylation.     

Electron and X-ray microscopic analyses of reaggregated materials obtained after fractionation of dissolved sporopollenin

Summary Exines fromTypha angustifolia L. pollen were dissolved in hot 2-aminoethanol. The solubilisate was successively fractionated and reaggregated via a dialysis cascade with dialysis tubings of different exclusion volumina. Four fractions of reaggregated material with different molecular mass were obtained. Fraction 1 with a molecular mass above 25,000 Da, fraction 2 with a molecular mass between 10,000–25,000 Da, fraction 3 with a molecular mass between 5,000–10,000 Da, and fraction 4 of a molecular mass lower than 5,000 Da. The fractions were comparatively analysed by scanning and transmission electron microscopy and X-ray microscopy. The material of the fractions with a molecular mass above 10,000 Da exhibit high congruence to the initial material. Analysis of the reaggregated material with the lowest molecular mass revealed special distinct substructures which in form and size showed high similarities to substructures of exines described in literature. In detail, spherical substructures consisting of an electron-dense core surrounded by an electron-transparent corona and in addition elongated substructures with a distinctive surface sculpture were detected.Abbreviations SEM scanning electron microscopy - TEM transmission electron microscopy     

Effect of vitamin D3 on behavioural and biochemical parameters in diabetes type 1‐induced rats

Diabetes is associated with long‐term complications in the brain and reduced cognitive ability. Vitamin D₃ (VD₃) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)‐induced diabetic rats. Our aim was to analyse the potential of VD₃ in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na⁺K⁺‐adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase (δ‐ALA‐D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ‐induced diabetic rats. Animals were divided into eight groups (n = 5): control/saline, control/metformin (Metf), control/VD₃, control/Metf + VD₃, diabetic/saline, diabetic/Metf, diabetic/VD₃ and diabetic/Metf + VD₃. Thirty days after treatment, animals were submitted to contextual fear‐conditioning and open‐field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ‐ALA‐D and Na⁺K⁺‐ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD₃ prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na⁺K⁺‐ATPase was reverted when compared with non‐treated rats, but the increase in δ‐ALA‐D activity was not. VD₃ prevented diabetes‐induced TBARS level and improved memory. Our results show that VD₃ can avoid cognitive deficit through prevention of changes in important enzymes such as Na⁺K⁺‐ATPase and AChE in cerebral cortex in type 1 diabetic rats. Copyright © 2014 John Wiley & Sons, Ltd.     

Arginine in Growing Cells of Sugarcane. Nutritional Effects, Uptake and Incorporation into Proteins

The growth of sugarcane cell cultures derived from parenchyma tissues of three different varieties of sugarcane showed a marked dependence on the presence of arginine when the cells were cultured in a synthetic liquid medium containing a mixture of amino acids. The cells appeared lo have access to n normal biosynthetic pathway of arginine biosynthesis but took up exogenously supplied arginine rapidly and efficiently. Arginine was not limiting for protein formation, nor were proteins with AN unusually high number of arginine residues evident. The low level of arginine effective in bringing about the growth response is suggestive of a regulatory function for this amino acid in sugarcane cells.     

Implication of the visual system in the regulation of activity cycles in the absence of solar light: 2-[125I]iodomelatonin binding sites and melatonin receptor gene expression in the brains of demersal deep-sea gadiform fish

Relative eye size, gross brain morphology and central localization of 2-[¹²⁵I]iodomelatonin binding sites and melatonin receptor gene expression were compared in six gadiform fish living at different depths in the north-east Atlantic Ocean: Phycis blennoides (capture depth range 265 to 1260 m), Nezumia aequalis (445 to 1512 m), Coryphaenoides rupestris (706 to 1932 m), Trachyrincus murrayi (1010 to 1884 m), Coryphaenoides guentheri (1030 m) and Coryphaenoides (Nematonurus) armatus (2172 to 4787 m). Amongst these, the eye size range was 0.15 to 0.35 of head length with a value of 0.19 for C. (N.) armatus, the deepest species. Brain morphology reflected behavioural differences with well-developed olfactory regions in P. blennoides, T. murrayi and C. (N.) armatus and evidence of olfactory deficit in N. aequalis, C. rupestris and C. guentheri. All species had a clearly defined optic tectum with 2-[¹²⁵I]iodomelatonin binding and melatonin receptor gene expression localized to specific brain regions in a similar pattern to that found in shallow-water fish. Melatonin receptors were found throughout the visual structures of the brains of all species. Despite living beyond the depth of penetration of solar light these fish have retained central features associated with the coupling of cycles of growth, behaviour and reproduction to the diel light–dark cycle. How this functions in the deep sea remains enigmatic.     

Behavioral Activity of Hydrocarbons Emitted by Honeybee Waggle Dancers

Waggle-dancing honeybee foragers emit four hydrocarbons that have been shown to stimulate colony foraging by reactivating experienced foragers and increasing the number of recruitment dances. These hydrocarbons, the alkanes tricosane and pentacosane, and the alkenes (Z)-9-tricosene and (Z)-9-pentacosene, are part of the array of social insects cuticular lipids which have been well studied in the context of nestmate recognition. This study seeks to determine which of the dance hydrocarbons produce the behavioral responses of forager bees by using a binary choice behavioral assay for attraction or repulsion to the volatile phase of the dance compounds. We found no significant deviation from random choice for single dance compounds and pairs of compounds, but bees were significantly attracted to a mixture of the three compounds (Z)-9-tricosene, tricosane, and pentacosane. These results suggest synergy among the waggle-dance hydrocarbons, which was unexpected based on previous research where, in the context of nestmate recognition, alkenes have been shown to play a key role in eliciting behavioral responses. Synergy among the waggle-dance hydrocarbons may provide specificity that facilitates adaptive, context-specific behavioral responses to this subset of cuticular hydrocarbons.