Genome-wide identification and characterization of putative cytochrome P450 genes in the model legume <Emphasis Type="Italic">Medicago truncatula</Emphasis>

In plants, cytochrome P450 is a group of monooxygenases existing as a gene superfamily and plays important roles in metabolizing physiologically important compounds. However, to date only a limited number of P450s have been identified and characterized in legumes. In this study, data mining methods were used, and 151 putative P450 genes in the model legume Medicago truncatula were identified, including 135 novel sequences. These genes were classified into 9 clans and 44 families by sequence similarity, and among those 4 new clans and 21 new families not reported previously in legumes. By comparison of these genes with P450 genes in Arabidopsis and rice, it was found that most of the known P450 families in dicot species exist in M. truncatula. The representative protein sequences of putative P450s were aligned, and the secondary elements were assigned based on the known structure P450BM3. Putative substrate recognition sites (SRSs) and substrate binding sites were also identified in these sequences. In addition, the ESTs-derived expression profiles (digital Northern) of the putative P450 genes were analyzed, which was confirmed by semi-quantitative RT-PCR analyses of several selected P450 genes. These results will provide a base for catalogue information on P450 genes in M. truncatula and for further functional analysis of P450 superfamily genes in legumes.     

ESTs library from embryonic stages reveals tubulin and reflectin diversity in Sepia officinalis (Mollusca — Cephalopoda)

New molecular resources regarding the so-called “non-standard models” in biology extend the present knowledge and are essential for molecular evolution and diversity studies (especially during the development) and evolutionary inferences about these zoological groups, or more practically for their fruitful management. Sepia officinalis, an economically important cephalopod species, is emerging as a new lophotrochozoan developmental model. We developed a large set of expressed sequence tags (ESTs) from embryonic stages of S. officinalis, yielding 19,780 non-redundant sequences (NRS). Around 75% of these sequences have no homologs in existing available databases. This set is the first developmental ESTs library in cephalopods. By exploring these NRS for tubulin, a generic protein family, and reflectin, a cephalopod specific protein family,we point out for both families a striking molecular diversity in S. officinalis.     

Shaping tubular carriers for intracellular membrane transport

The particular compositions of the intracellular membrane organelles rely on the proteins and lipids received frequently through membrane trafficking. The delivery of these molecules is driven by the membrane-bound organelles known as transport carriers (TCs). Advanced microscopy approaches have revealed that TC morphology ranges from small vesicles to complex tubular membrane structures. These tubular TCs (TTCs) support effectively both sorting and transport events within the biosynthetic and endocytic pathways, while a coherent picture of the processes that define the formation and further fate of TTCs is still missing. Here, we present an overview of the mechanisms operating during the TTC life cycle, as well as of the emerging role of tubular carriers in different intracellular transport routes.     

Lycopersicon esculentum lectin is a marker of transient amplifying cells in in vitro cultures of isolated limbal stem cells

The maintenance of a healthy corneal epithelium under both normal and wound healing conditions is achieved by a population of stem cells (SCs) located in the basal epithelium at the corneoscleral limbus. In the light of the development of strategies for reconstruction of the ocular surface in patients with limbal stem cell deficiency, a major challenge in corneal SCs biology remains the ability to identify stem cells in situ and in vitro. To date, not so much markers exist for the identification of different phenotypes. CESCs (corneal epithelial stem cells) isolated from limbal biopsies were maintained in primary culture for 14 days and stained with Hoechst and a panel of FITC-conjugated lectins. All lectins, with the exception of Lycopersicon esculentum, labelled CESCs irrespective of the degree of differentiation. Lycopersicon esculentum, that binds N-acetylglucosamine oligomers, labelled intensely only the surface of TACs (single corneal epithelial stem cells better than colonial cells). These results suggest that Lycopersicon esculentum lectin is a useful and easy-to-use marker for the in vitro identification of TACs (transient amplifying cells) in cultures of isolated CESCs.     

Variations of chromosomes 2 and 3 gene expression profiles among pulmonary telocytes,pneumocytes, airway cells,mesenchymal stem cells and lymphocytes

Telocytes (TCs) were identified as a distinct cellular type of the interstitial tissue and defined as cells with extremely long telopodes (Tps). Our previous data demonstrated patterns of mouse TC‐specific gene profiles on chromosome 1. The present study focuses on the identification of characters and patterns of TC‐specific or TC‐dominated gene expression profiles in chromosome 2 and 3, the network of principle genes and potential functional association. We compared gene expression profiles of pulmonary TCs, mesenchymal stem cells, fibroblasts, alveolar type II cells, airway basal cells, proximal airway cells, CD8⁺T cells from bronchial lymph nodes (T‐BL), and CD8⁺ T cells from lungs (T‐LL). We identified that 26 or 80 genes of TCs in chromosome 2 and 13 or 59 genes of TCs up‐ or down‐regulated in chromosome 3, as compared with other cells respectively. Obvious overexpression of Myl9 in chromosome 2 of TCs different from other cells, indicates that biological functions of TCs are mainly associated with tissue/organ injury and ageing, while down‐expression of Pltp implies that TCs may be associated with inhibition or reduction of inflammation in the lung. Dominant overexpression of Sh3glb1, Tm4sf1 or Csf1 in chromosome 3 of TCs is mainly associated with tumour promotion in lung cancer, while most down‐expression of Pde5 may be involved in the development of pulmonary fibrosis and other acute and chronic interstitial lung disease.     

四环素类抗生素降解途径及其主要降解产物研究进展

四环素类抗生素在生产和贮存过程中会发生一系列非生物降解反应,其中某些代谢及降解产物,与母体相比,虽然其活性降低,但毒性却大大增强.此类抗生素随着畜禽废弃物等途径进入到环境中,随环境条件的不同将发生一种或多种降解反应,其降解方式除了非生物降解外,还包括生物降解.本文综述了四环素类抗生素在不同生态环境中的降解途径以及降解产物,并对今后的研究方向进行了探计,旨在为其生态风险评价提供有价值的参考.