Somatic embryogenesis and plant regeneration from undeveloped ovules and stigma/style explants of sweet orange navel group [ Citrus sinensis (L.) Osb.]

Somatic embryogenesis was induced and plant regeneration was obtained in 11 different genotypes of sweet orange navel group [Citrus sinensis (L.) Osb.] from cultures of stigma/style explants and undeveloped ovules. Explants were cultured on 3 different modifications of Murashige and Skoog medium: 500 mg l-1 malt extract; 500 mg l-1 malt extract and 4.6 μM kinetin; and 500 mg l-1 malt extract and 13.3 μM 6-benzylaminopurine. Sucrose (146 mM) was used as carbon source. Somatic embryogenesis occurred 1–3 months after culture initiation from undeveloped ovule and stigma/style cultures of all the genotypes tested. Somatic embryos developed into plantlets with a high frequency (74%) after transfer to Murashige and Skoog medium supplemented with 146 mM sucrose and 500 mg l-1 malt extract. Plants were successfully transferred to soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

OntoGene in BioCreative II

Background:

Research scientists and companies working in the domains of biomedicine and genomics are increasingly faced with the problem of efficiently locating, within the vast body of published scientific findings, the critical pieces of information that are needed to direct current and future research investment.

Results:

In this report we describe approaches taken within the scope of the second BioCreative competition in order to solve two aspects of this problem: detection of novel protein interactions reported in scientific articles, and detection of the experimental method that was used to confirm the interaction. Our approach to the former problem is based on a high-recall protein annotation step, followed by two strict disambiguation steps. The remaining proteins are then combined according to a number of lexico-syntactic filters, which deliver high-precision results while maintaining reasonable recall. The detection of the experimental methods is tackled by a pattern matching approach, which has delivered the best results in the official BioCreative evaluation.

Conclusion:

Although the results of BioCreative clearly show that no tool is sufficiently reliable for fully automated annotations, a few of the proposed approaches (including our own) already perform at a competitive level. This makes them interesting either as standalone tools for preliminary document inspection, or as modules within an environment aimed at supporting the process of curation of biomedical literature.

     

Involvement of KCNQ2 subunits in [3H]dopamine release triggered by depolarization and pre-synaptic muscarinic receptor activation from rat striatal synaptosomes

KCNQ2 and KCNQ3 subunits encode for the muscarinic-regulated current (I(KM)), a sub-threshold voltage-dependent K+ current regulating neuronal excitability. In this study, we have investigated the involvement of I(KM) in dopamine (DA) release from rat striatal synaptosomes evoked by elevated extracellular K+ concentrations ([K+]e) and by muscarinic receptor activation. [3H]dopamine ([3H]DA) release triggered by 9 mmol/L [K+]e was inhibited by the I(KM) activator retigabine (0.01-30 micromol/L; Emax = 54.80 +/- 3.85%; IC50 = 0.50 +/- 0.36 micromol/L). The I(KM) blockers tetraethylammonium (0.1-3 mmol/L) and XE-991 (0.1-30 micromol/L) enhanced K+-evoked [3H]DA release and prevented retigabine-induced inhibition of depolarization-evoked [3H]DA release. Retigabine-induced inhibition of K+-evoked [3H]DA release was also abolished by synaptosomal entrapment of blocking anti-KCNQ2 polyclonal antibodies, an effect prevented by antibody pre-absorption with the KCNQ2 immunizing peptide. Furthermore, the cholinergic agonist oxotremorine (OXO) (1-300 micromol/L) potentiated 9 mmol/L [K+]e-evoked [3H]DA release (Emax = 155 +/- 9.50%; EC50 = 25 +/- 1.80 micromol/L). OXO (100 micromol/L)-induced [3H]DA release enhancement was competitively inhibited by pirenzepine (1-10 nmol/L) and abolished by the M3-preferring antagonist 4-diphenylacetoxy N-methylpiperidine methiodide (1 micromol/L), but was unaffected by the M1-selective antagonist MT-7 (10-100 nmol/L) or by Pertussis toxin (1.5-3 microg/mL), which uncouples M2- and M4-mediated responses. Finally, OXO-induced potentiation of depolarization-induced [3H]DA release was not additive to that produced by XE-991 (10 micromol/L), was unaffected by retigabine (10 micromol/L), and was abolished by synaptosomal entrapment of anti-KCNQ2 antibodies. Collectively, these findings indicate that, in rat striatal nerve endings, I(KM) channels containing KCNQ2 subunits regulate depolarization-induced DA release and that I(KM) suppression is involved in the reinforcement of depolarization-induced DA release triggered by the activation of pre-synaptic muscarinic heteroreceptors.     

Impaired hepatic function and central dopaminergic denervation in a rodent model of Parkinson's disease: A self-perpetuating crosstalk?

In Parkinson's disease (PD), aside from the central lesion, involvement of visceral organs has been proposed as part of the complex clinical picture of the disease. The issue is still poorly understood and relatively unexplored. In this study we used a classic rodent model of nigrostriatal degeneration, induced by the intrastriatal injection of 6-hydroxydopamine (6-OHDA), to investigate whether and how a PD-like central dopaminergic denervation may influence hepatic functions. Rats received an intrastriatal injection of 6-OHDA or saline (sham), and blood, cerebrospinal fluid, liver and brain samples were obtained for up to 8 weeks after surgery. Specimens were analyzed for changes in cytokine and thyroid hormone levels, as well as liver mitochondrial alterations. Hepatic mitochondria isolated from animals bearing extended nigrostriatal lesion displayed increased ROS production, while membrane potential (ΔΨ) and ATP production were significantly decreased. Reduced ATP production correlated with nigral neuronal loss. Thyroid hormone levels were significantly increased in serum of PD rats compared to sham animals while steady expression of selected cytokines was detected in all groups. Hepatic enzyme functions were comparable in all animals. Our study indicates for the first time that in a rodent model of PD, hepatic mitochondria dysfunctions arise as a consequence of nigrostriatal degeneration, and that thyroid hormone represents a key interface in this CNS-liver interaction. Liver plays a fundamental detoxifying function and a better understanding of PD-related hepatic mitochondrial alterations, which might further promote neurodegeneration, may represent an important step for the development of novel therapeutic strategies.     

Rat forming incisor requires a rigorous ECM remodeling modulated by MMP/RECK balance

Reversion-inducing-cysteine-rich protein with Kazal motifs (RECK) is a single membrane-anchored MMP-regulator and regulates matrix metalloproteinases (MMP) 2, 9 and 14. In turn, MMPs are endopeptidases that play a pivotal role in remodeling ECM. In this work, we decided to evaluate expression pattern of RECK in growing rat incisor during, specifically focusing out amelogenesis process. Based on different kinds of ameloblasts, our results showed that RECK expression was conducted by secretory and post-secretory ameloblasts. At the secretory phase, RECK was localized in the infra-nuclear region of the ameloblast, outer epithelium, near blood vessels, and in the stellate reticulum. From the transition to the maturation phases, RECK was strongly expressed by non-epithelial immuno-competent cells (macrophages and/or dendritic-like cells) in the papillary layer. From the transition to the maturation stage, RECK expression was increased. RECK mRNA was amplified by RT-PCR from whole enamel organ. Here, we verified the presence of RECK mRNA during all stages of amelogenesis. These events were governed by ameloblasts and by non-epithelial cells residents in the enamel organ. Concluding, we found differential expression of MMPs-2, -9 and RECK in the different phases of amelogenesis, suggesting that the tissue remodeling is rigorously controlled during dental mineralization.     

Cofeeding intra‐ and interspecific transmission of an emerging insect‐borne rickettsial pathogen

Cat fleas (Ctenocephalides felis) are known as the primary vector and reservoir of Rickettsia felis, the causative agent of flea‐borne spotted fever; however, field surveys regularly report molecular detection of this infectious agent from other blood‐feeding arthropods. The presence of R. felis in additional arthropods may be the result of chance consumption of an infectious bloodmeal, but isolation of viable rickettsiae circulating in the blood of suspected vertebrate reservoirs has not been demonstrated. Successful transmission of pathogens between actively blood‐feeding arthropods in the absence of a disseminated vertebrate infection has been verified, referred to as cofeeding transmission. Therefore, the principal route from systemically infected vertebrates to uninfected arthropods may not be applicable to the R. felis transmission cycle. Here, we show both intra‐ and interspecific transmission of R. felis between cofeeding arthropods on a vertebrate host. Analyses revealed that infected cat fleas transmitted R. felis to naïve cat fleas and rat fleas (Xenopsylla cheopis) via fleabite on a nonrickettsemic vertebrate host. Also, cat fleas infected by cofeeding were infectious to newly emerged uninfected cat fleas in an artificial system. Furthermore, we utilized a stochastic model to demonstrate that cofeeding is sufficient to explain the enzootic spread of R. felis amongst populations of the biological vector. Our results implicate cat fleas in the spread of R. felis amongst different vectors, and the demonstration of cofeeding transmission of R. felis through a vertebrate host represents a novel transmission paradigm for insect‐borne Rickettsia and furthers our understanding of this emerging rickettsiosis.     

Muscle differentiation in a colonial ascidian: organisation, gene expression and evolutionary considerations

Background  

Ascidians are tunicates, the taxon recently proposed as sister group to the vertebrates. They possess a chordate-like swimming larva, which metamorphoses into a sessile adult. Several ascidian species form colonies of clonal individuals by asexual reproduction. During their life cycle, ascidians present three muscle types: striated in larval tail, striated in the heart, and unstriated in the adult body-wall.     

Evaluation of Toll-Like Receptor 2 and 4 RNA Expression and the Cytokine Profile in Postmenopausal Women with Metabolic Syndrome

Objective

To evaluate the gene expression of Toll-Like (TLR-2 and TLR-4) receptors and cytokine profile in postmenopausal women with or without metabolic syndrome (MetS).

Methods

In this cross-sectional study, 311 Brazilian women (age≥45 years and amenorrhea≥12 months) were included. Women showing three or more of the following diagnostic criteria were diagnosed as positive for MetS: waist circumference>88 cm, triglycerides≥150 mg/dL, HDL cholesterol<50 mg/dL, blood pressure≥130/85 mmHg, and fasting glucose≥100 mg/dL. The expression of TLR-2 and TLR-4 in peripheral blood was evaluated by RNA extraction and subsequent real time PCR analysis. The cytokine profile, tumor necrosis factor alpha (TNF-α) and interleukins 1β, 6, and 10, were measured by ELISA.

Results

The expression of TLR-2 RNA was demonstrated in 32.5% and TLR-4 in 20.6% of the subjects. There was no association between the expression of TLR-2 and TLR-4 and the presence or absence of MetS (P>0.05). A greater production of IL-6 was associated with TLR-2 and TLR-4 expressions and greater production of TNF-α was associated only with TLR-2 expression (P>0.05). Only the lower quartile of IL-10 was associated with the presence of the MetS (P>0.05).

Conclusions

TLR-2 and TLR-4 expressions were associated with increased pro-inflammatory cytokines, IL-6 and TNF-α, with no association with biomarkers of MetS. The low concentrations of IL-10 may suggest an anti-inflammatory modulation in postmenopausal women with MetS.