Aquaporin-6 is expressed along the rat gastrointestinal tract and upregulated by feeding in the small intestine

Background  

Several aquaporins (a family of integral membrane proteins) have been recently identified in the mammalian gastrointestinal tract, and their involvement in the movement of fluid and small solutes has been suggested. In this direction we investigated, in some regions of the rat gastrointestinal tract, the presence and localization of aquaporin-6, given its peculiar function as an ion selective channel.     

Basement membrane deposition of nidogen 1 but not nidogen 2 requires the nidogen binding module of the laminin gamma1 chain

The nidogen-laminin interaction is proposed to play a key role in basement membrane (BM) assembly. However, though there are similarities, the phenotypes in mice lacking nidogen 1 and 2 (nidogen double null) differ to those of mice lacking the nidogen binding module (γ1III4) of the laminin γ1 chain. This indicates different cell- and tissue-specific functions for nidogens and their interaction with laminin and poses the question of whether the phenotypes in nidogen double null mice are caused by the loss of the laminin-nidogen interaction or rather by other unknown nidogen functions. To investigate this, we analyzed BMs, in particular those in the skin of mice lacking the nidogen binding module. In contrast to nidogen double null mice, all skin BMs in γ1III4-deficient mice appeared normal. Furthermore, although nidogen 1 deposition was strongly reduced, nidogen 2 appeared unchanged. Mice with additional deletion of the laminin γ3 chain, which contains a γ1-like nidogen binding module, showed a further reduction of nidogen 1 in the dermoepidermal BM; however, this again did not affect nidogen 2. This demonstrates that in vivo only nidogen 1 deposition is critically dependent on the nidogen binding modules of the laminin γ1 and γ3 chains, whereas nidogen 2 is independently recruited either by binding to an alternative site on laminin or to other BM proteins.     

Polyploidization as a retraction force in plant genome evolution: sequence rearrangements in triticale

Background

Polyploidization is a major evolutionary process in plants where hybridization and chromosome doubling induce enormous genomic stress and can generate genetic and epigenetic modifications. However, proper evaluation of DNA sequence restructuring events and the precise characterization of sequences involved are still sparse.

Methodology/Principal Findings

Inter Retrotransposons Amplified Polymorphism (IRAP), Retrotransposons Microsatellite Amplified Polymorphism (REMAP) and Inter Simple Sequence Repeat (ISSR) largely confirmed the absence of any intraspecific variation in wheat, rye and triticale. The comparative analysis of banding profiles between wheat and rye inbred lines revealed 34% of monomorphic (common to both parental species) bands for the ten different primer combinations used. The analysis of triticale plants uncovered nearly 51% of rearranged bands in the polyploid, being the majority of these modifications, due to the loss of rye bands (83%). Sequence analysis of rye fragments absent in triticale revealed for instance homology with hydroxyproline-rich glycoproteins (HRGP), a protein that belongs to a major family of inducible defence response proteins. Conversely, a wheat-specific band absent in triticale comprises a nested structure of copia-like retrotransposons elements, namely Claudia and Barbara. Sequencing of a polyploid-specific band (absent in both parents) revealed a microsatellite related sequence. Cytological studies using Fluorescent In Situ Hybridization (FISH) with REMAP products revealed a widespread distribution of retrotransposon and/or microsatellite flanking sequences on rye chromosomes, with a preferential accumulation in heterochromatic sub-telomeric domains.

Conclusions/Significance

Here, we used PCR-based molecular marker techniques involving retrotransposons and microsatellites to uncover polyploidization induced genetic restructuring in triticale. Sequence analysis of rearranged genomic fragments either from rye or wheat origin showed these to be retrotransposon-related as well as coding sequences. Further FISH analysis revealed possible chromosome hotspots for sequence rearrangements. The role of chromatin condensation on the origin of genomic rearrangements mediated by polyploidization in triticale is also discussed.     

Mechanism of nucleocapsid protein catalyzed structural isomerization of the dimerization initiation site of HIV-1

Dimerization of two homologous strands of genomic RNA is an essential feature of retroviral replication. In the human immunodeficiency virus type 1 (HIV-1), a conserved stem-loop sequence, the dimerization initiation site (DIS), has been identified as the domain primarily responsible for initiation of this aspect of viral assembly. The DIS loop contains an autocomplementary hexanucleotide sequence flanked by highly conserved 5' and 3' purines and can form a homodimer through a loop-loop kissing interaction. In a structural rearrangement activated by the HIV-1 nucleocapsid protein (NCp7) and considered to be associated with viral particle maturation, the DIS dimer converts from an intermediate kissing to an extended duplex isoform. Using 2-aminopurine (2-AP) labeled sequences derived from the DIS(Mal) variant and fluorescence methods, the two DIS dimer isoforms have been unambiguously distinguished, allowing a detailed examination of the kinetics of this RNA structural isomerization and a characterization of the role of NCp7 in the reaction. In the presence of divalent cations, the DIS kissing dimer is found to be kinetically trapped and converts to the extended duplex isoform only upon addition of NCp7. NCp7 is demonstrated to act catalytically in inducing the structural isomerization by accelerating the rate of strand exchange between the two hairpin stem helices, without disruption of the loop-loop helix. Observation of an apparent maximum conversion rate for NCp7-activated DIS isomerization, however, requires protein concentrations in excess of the 2:1 stoichiometry estimated for high-affinity NCp7 binding to the DIS kissing dimer, indicating that transient interactions with additional NCp7(s) may be required for catalysis.     

Phytotoxicity, not nitrogen immobilization, explains plant litter inhibitory effects: evidence from solid-state 13C NMR spectroscopy

Litter decomposition provides nutrients that sustain ecosystem productivity, but litter may also hamper root proliferation. The objectives of this work were to assess the inhibitory effect of litter decomposition on seedling growth and root proliferation; to study the role of nutrient immobilization and phytotoxicity; and to characterize decomposing litter by (13)C NMR spectroscopy. A litter-bag experiment was carried out for 180 d with 16 litter types. Litter inhibitory effects were assessed by two bioassays: seed germination and root proliferation bioassays. Activated carbon (C) and nutrient solutions were used to evaluate the effects of phytotoxic factors and nutrient immobilization. An inhibitory effect was found for all species in the early phase of decomposition, followed by a decrease over time. The addition of activated C to litter removed this inhibition. No evidence of nutrient immobilization was found in the analysis of nitrogen dynamics. NMR revealed consistent chemical changes during decomposition, with a decrease in O-alkyl and an increase in alkyl and methoxyl C. Significant correlations were found among inhibitory effects, the litter decay rate and indices derived from NMR. The results show that it is possible to predict litter inhibitory effects across a range of litter types on the basis of their chemical composition.     

Identification of differentially expressed microRNAs by microarray: a possible role for microRNA genes in pituitary adenomas

MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by targeting mRNA. It has been demonstrated that miRNA expression is altered in many human cancers, suggesting that they may play a role in human neoplasia. To determine whether miRNA expression is altered in pituitary adenomas, we analyzed the entire miRNAome in 32 pituitary adenomas and in 6 normal pituitary samples by microarray and by Real-Time PCR. Here, we show that 30 miRNAs are differentially expressed between normal pituitary and pituitary adenomas. Moreover, 24 miRNAs were identified as a predictive signature of pituitary adenoma and 29 miRNAs were able to predict pituitary adenoma histotype. miRNA expression could differentiate micro- from macro-adenomas and treated from non-treated patient samples. Several of the identified miRNAs are involved in cell proliferation and apoptosis, suggesting that their deregulated expression may be involved in pituitary tumorigenesis. Predictive miRNAs could be potentially useful diagnostic markers, improving the classification of pituitary adenomas.     

Efficacy of plant extracts against stored-products fungi

The fungistatic activity of six aqueous extracts of plants were tested against Aspergillus candidus, Aspergillus niger, Penicillium sp. and Fusarium culmorum. The plants were, chamomile (Anthemis nobilis L.), cinnamon (Cinnamomum verum J. Presl.), French lavender (Lavandula stoechas L.), garlic (Allium sativum L.), malva (Malva sylvestris L.) and peppermint (Mentha piperita L.). The more concentrated extracts of chamomile and malva inhibited totally the growth of the tested fungi with malva the most effective one.