Cold storage to overcome dormancy affects the carbohydrate status and photosynthetic capacity of Rhododendron simsii

Global warming leads to increasing irregular and unexpected warm spells during autumn, and therefore natural chilling requirements to break dormancy are at risk. Controlled cold treatment can provide an answer to this problem. Nevertheless, artificial cold treatment will have consequences for carbon reserves and photosynthesis. In this paper, the effect of dark cold storage at 7 °C to break flower bud dormancy in the evergreen Rhododendron simsii was quantified. Carbohydrate and starch content in leaves and flower buds of an early (‘Nordlicht’), semi‐early (‘M. Marie’) and late (‘Mw. G. Kint’) flowering cultivar showed that carbon loss due to respiration was lowest in ‘M. Marie’, while ‘Mw. G. Kint’ was completely depleted of starch reserves at the end of cold treatment. Gene isolation resulted in a candidate gene for sucrose synthase (SUS) RsSus, which appears to be homologous to AtSus3 and had a clear increase in expression in leaves during cold treatment. Photosynthesis measurements on ‘Nordlicht’ and the late‐flowering cultivar ‘Thesla’ showed that during cold treatment, dark respiration decreased 58% and 63%, respectively. Immediately after cold treatment, dark respiration increased and stabilised after 3 days. The light compensation point followed the same trend as dark respiration. Quantum efficiency showed no significant changes during the first days after cold treatment, but was significantly higher than in plants with dormant flower buds at the start of cold treatment. In conclusion, photosynthesis stabilised 3 days after cold treatment and was improved compared to the level before cold treatment.     

ROS Production via P2Y1-PKC-NOX2 Is Triggered by Extracellular ATP after Electrical Stimulation of Skeletal Muscle Cells

During exercise, skeletal muscle produces reactive oxygen species (ROS) via NADPH oxidase (NOX2) while inducing cellular adaptations associated with contractile activity. The signals involved in this mechanism are still a matter of study. ATP is released from skeletal muscle during electrical stimulation and can autocrinely signal through purinergic receptors; we searched for an influence of this signal in ROS production. The aim of this work was to characterize ROS production induced by electrical stimulation and extracellular ATP. ROS production was measured using two alternative probes; chloromethyl-2,7- dichlorodihydrofluorescein diacetate or electroporation to express the hydrogen peroxide-sensitive protein Hyper. Electrical stimulation (ES) triggered a transient ROS increase in muscle fibers which was mimicked by extracellular ATP and was prevented by both carbenoxolone and suramin; antagonists of pannexin channel and purinergic receptors respectively. In addition, transient ROS increase was prevented by apyrase, an ecto-nucleotidase. MRS2365, a P2Y₁ receptor agonist, induced a large signal while UTPyS (P2Y₂ agonist) elicited a much smaller signal, similar to the one seen when using ATP plus MRS2179, an antagonist of P2Y₁. Protein kinase C (PKC) inhibitors also blocked ES-induced ROS production. Our results indicate that physiological levels of electrical stimulation induce ROS production in skeletal muscle cells through release of extracellular ATP and activation of P2Y1 receptors. Use of selective NOX2 and PKC inhibitors suggests that ROS production induced by ES or extracellular ATP is mediated by NOX2 activated by PKC.     

Molecular modeling of <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> glutamate cysteine ligase and investigation of its interactions with glutathione

Trypanosoma cruzi glutamate cysteine ligase (TcGCL) is considered a potential drug target to develop novel antichagasic drugs. We have used a variety of computational methods to investigate the interactions between TcGCL with Glutathione (GSH). The three-dimensional structure of TcGCL was constructed by comparative modeling methods using the Saccharomyces cerevisiae glutamate cysteine ligase as template. Molecular dynamics simulations were used to validate the TcGCL model and to analyze the molecular interactions with GSH. Using RMSD clustering, the most prevalent GSH binding modes were identified paying attention to the residues involved in the molecular interactions. The GSH binding modes were used to propose pharmacophore models that can be exploited in further studies to identify novel antichagasic compounds.     

The development of cephalic armor in the tokay gecko (Squamata: Gekkonidae: Gekko gecko)

Armored skin resulting from the presence of bony dermal structures, osteoderms, is an exceptional phenotype in gekkotans (geckos and flap-footed lizards) only known to occur in three genera: Geckolepis, Gekko, and Tarentola. The Tokay gecko (Gekko gecko LINNAEUS 1758) is among the best-studied geckos due to its large size and wide range of occurrence, and although cranial dermal bone development has previously been investigated, details of osteoderm development along a size gradient remain less well-known. Likewise, a comparative survey of additional species within the broader Gekko clade to determine the uniqueness of this trait has not yet been completed. Here, we studied a large sample of gekkotans (38 spp.), including 18 specimens of G. gecko, using X-rays and high-resolution computed tomography for visualizing and quantifying the dermal armor in situ. Results from this survey confirm the presence of osteoderms in a second species within this genus, Gekko reevesii GRAY 1831, which exhibits discordance in timing and pattern of osteoderm development when compared with its sister taxon, G. gecko. We discuss the developmental sequence of osteoderms in these two species and explore in detail the formation and functionality of these enigmatic dermal ossifications. Finally, we conducted a comparative analysis of endolymphatic sacs in a wide array of gekkotans to explore previous ideas regarding the role of osteoderms as calcium reservoirs. We found that G. gecko and other gecko species with osteoderms have highly enlarged endolymphatic sacs relative to their body size, when compared to species without osteoderms, which implies that these membranous structures might fulfill a major role of calcium storage even in species with osteoderms.     

Conversion of olive tree biomass into fermentable sugars by dilute acid pretreatment and enzymatic saccharification

The production of fermentable sugars from olive tree biomass was studied by dilute acid pretreatment and further saccharification of the pretreated solid residues. Pretreatment was performed at 0.2%, 0.6%, 1.0% and 1.4% (w/w) sulphuric acid concentrations while temperature was in the range 170-210 degrees C. Attention is paid to sugar recovery both in the liquid fraction issued from pretreatment (prehydrolysate) and that in the water-insoluble solid (WIS). As a maximum, 83% of hemicellulosic sugars in the raw material were recovered in the prehydrolysate obtained at 170 degrees C, 1% sulphuric acid concentration, but the enzyme accessibility of the corresponding pretreated solid was not very high. In turn, the maximum enzymatic hydrolysis yield (76.5%) was attained from a pretreated solid (at 210 degrees C, 1.4% acid concentration) in which cellulose solubilization was detected; moreover, sugar recovery in the prehydrolysate was the poorest one among all the experiments performed. To take account of fermentable sugars generated by pretreatment and the glucose released by enzymatic hydrolysis, an overall sugar yield was calculated. The maximum value (36.3 g sugar/100 g raw material) was obtained when pretreating olive tree biomass at 180 degrees C and 1% sulphuric acid concentration, representing 75% of all sugars in the raw material. Dilute acid pretreatment improves results compared to water pretreatment.     

Semliki Forest Virus Expressing Interleukin-12 Induces Antiviral and Antitumoral Responses in Woodchucks with Chronic Viral Hepatitis and Hepatocellular Carcinoma

A vector based on Semliki Forest virus (SFV) expressing high levels of interleukin-12 (SFV-enhIL-12) has previously demonstrated potent antitumoral efficacy in small rodents with hepatocellular carcinoma (HCC) induced by transplantation of tumor cells. In the present study, the infectivity and antitumoral/antiviral effects of SFV vectors were evaluated in the clinically more relevant woodchuck model, in which primary HCC is induced by chronic infection with woodchuck hepatitis virus (WHV). Intratumoral injection of SFV vectors expressing luciferase or IL-12 resulted in high reporter gene activity within tumors and cytokine secretion into serum, respectively, demonstrating that SFV vectors infect woodchuck tumor cells. For evaluating antitumoral efficacy, woodchuck tumors were injected with increasing doses of SFV-enhIL-12, and tumor size was measured by ultrasonography following treatment. In five (83%) of six woodchucks, a dose-dependent, partial tumor remission was observed, with reductions in tumor volume of up to 80%, but tumor growth was restored thereafter. Intratumoral treatment further produced transient changes in WHV viremia and antigenemia, with ≥1.5-log₁₀ reductions in serum WHV DNA in half of the woodchucks. Antitumoral and antiviral effects were associated with T-cell responses to tumor and WHV antigens and with expression of CD4 and CD8 markers, gamma interferon, and tumor necrosis factor alpha in peripheral blood mononuclear cells, suggesting that immune responses against WHV and HCC had been induced. These experimental observations suggest that intratumoral administration of SFV-enhIL-12 may represent a strategy for treatment of chronic HBV infection and associated HCC in humans but indicate that this approach could benefit from further improvements.Hepatocellular carcinoma (HCC) is a major public health problem worldwide, representing the fifth most common type of cancer. HCC is also the third leading cause of cancer-related death, mainly because only surgical and local ablative therapeutic options have shown efficacy in patients with this type of cancer (21). Approximately 80% of all HCC cases are attributed to chronic infection with hepatitis C virus and/or hepatitis B virus (HBV). Chronic carriers of HBV have a greater than 100-fold-increased relative risk of developing HCC compared to HBV-uninfected humans, with an annual incidence rate of 2 to 6% in cirrhotic patients. The high incidence of HCC, together with its poor prognosis and limited therapeutic options, warrants the development of new treatment strategies for this disease.There is increasing evidence that stimulation of the immune system for subsequent recognition and killing of tumor cells may be a valuable treatment option for liver cancer. In general, HCC appears to be an attractive target for immunotherapy because cases of spontaneous tumor regression have been reported, HCC is often infiltrated with lymphocytes, and HCC-associated proteins such as alpha-fetoprotein may be used as targets for immune-mediated killing of tumors (5, 49).A promising strategy to stimulate the deficient antitumoral immune response is based on the transfer and subsequent expression of immunostimulatory genes in tumor cells using viral or nonviral delivery vectors. One of the most effective immunostimulatory cytokines is interleukin-12 (IL-12), a protein usually expressed by macrophages and dendritic cells. IL-12 has been demonstrated to induce strong antitumoral effects that are mediated by the stimulation of T-helper cell type 1 (Th1) responses, including the activation of cytolytic T lymphocytes (CTL) and natural killer cells, and by the inhibition of angiognesis (48, 50). All of these effects are dependent on the production of gamma interferon (IFN-γ). Viral vectors that are based on adenovirus have been used to deliver IL-12 into several animal models with transplantable HCC, resulting in a localized expression of this cytokine and usually leading to antitumoral effects (3, 14, 37). However, and despite successful treatment of HCC in preclinical studies, a phase I clinical trial with a first-generation adenoviral vector for delivery and expression of IL-12 in patients with primary and metastatic liver cancer produced only a modest antitumoral effect (41). This poor response was probably due to the low and transient IL-12 expression in tumors. These results in humans indicated a need for vectors with higher potency and for preclinical testing in relevant models of HCC (i.e., large animals with spontaneous tumors).Vectors based on Semliki Forest virus (SFV), a member of the alphavirus group, are highly efficient in inducing antitumoral responses in a variety of animal models (2, 9, 10, 39, 44, 53). The SFV vector used in the present study is based on a viral RNA genome in which the region coding for the structural proteins has been replaced by a heterologous gene (24). Recombinant SFV RNA can be transcribed in vitro and transfected into cells, resulting in viral replication and subsequent production of a subgenomic RNA from which the heterologous protein is expressed at very high levels. Recombinant SFV RNA can be packaged into viral particles (vp) by cotransfecting it into cells together with two helper RNAs coding for the capsid and the envelope proteins (43). Compared to adenoviral vectors expressing IL-12, tumor treatment with SFV vectors expressing the same cytokine resulted in greater antitumoral effects in a murine colon adenocarcinoma model and also in a rat orthotopic HCC model (16, 39). The greater antitumoral effect mediated by SFV vectors has been attributed to the higher expression of IL-12 and to the induction of apoptosis caused by SFV replication within tumor cells. Apoptosis leads to the release of tumor antigens that can be taken up by antigen-presenting cells, thereby potentiating the antitumoral response induced by IL-12 (54). Furthermore, SFV vectors have low immunogenicity when delivered intratumorally, allowing repetitive administrations into the same tumor, which is not possible with adenoviral vectors (38).In the present study, the antitumoral efficacy of an SFV vector expressing IL-12 (SFV-enhIL-12) was investigated in woodchucks with HCC. The Eastern woodchuck (Marmota monax) is frequently infected with the woodchuck hepatitis virus (WHV), which is closely related to the human HBV in its structure, genomic organization, mechanism of replication, and course of infection (29). The woodchuck has been used as a mammalian model for research on HBV, including the pathogenesis of acute and chronic HBV infection, and for preclinical evaluation of the safety and efficacy of candidate antiviral drugs and therapeutic immunomodulators for the treatment of chronic HBV infection (29) and prevention of HCC (47).All woodchucks chronically infected with WHV as neonates develop HCC, and the median time for tumor appearance is 24 months of age (34, 47). After identification of HCC, the median survival time of woodchucks is 6 months, a situation similar to that for patients with HCC. In addition, WHV-induced hepatocarcinogenesis shows strong similarity to HBV-induced carcinogenesis in humans (34, 47). These features of HCC that are associated with persistent hepatitis virus infection make the woodchuck model unique compared to other animal models, in which HCC is induced by a chemical carcinogen or by transplantation of established tumor cell lines into immune-deficient or immune-compatible hosts. Woodchucks with large liver tumors that acquire malignant characteristics in a stepwise process similar to HCC in humans are an attractive and suitable model for the preclinical evaluation of new treatment strategies for HBV-induced HCC in humans (47).The antitumoral efficacy of a SFV vector expressing high levels of IL-12 (SFV-enhIL-12) was investigated in six woodchucks with established chronic WHV infection and primary HCC. The results demonstrate that SFV-delivered IL-12 expression produced a dose-dependent, partial tumor remission that was associated with a general activation of cellular immune responses against HCC. The antitumoral activity, in addition to an antiviral activity against WHV, and the favorable safety profile in woodchucks suggest that a therapeutic approach based on SFV-enhIL-12 may represent a treatment strategy for HCC in patients with chronic HBV infection, but the overall results also indicate that this approach needs further improvement for inducing a complete tumor remission.     

Oxidative stress in cyanobacteria

Reactive oxygen species (ROS) are byproducts of aerobic metabolism and potent agents that cause oxidative damage. In oxygenic photosynthetic organisms such as cyanobacteria, ROS are inevitably generated by photosynthetic electron transport, especially when the intensity of light-driven electron transport outpaces the rate of electron consumption during CO₂ fixation. Because cyanobacteria in their natural habitat are often exposed to changing external conditions, such as drastic fluctuations of light intensities, their ability to perceive ROS and to rapidly initiate antioxidant defences is crucial for their survival. This review summarizes recent findings and outlines important perspectives in this field.     

Consequences of Lineage-Specific Gene Loss on Functional Evolution of Surviving Paralogs: ALDH1A and Retinoic Acid Signaling in Vertebrate Genomes

Genome duplications increase genetic diversity and may facilitate the evolution of gene subfunctions. Little attention, however, has focused on the evolutionary impact of lineage-specific gene loss. Here, we show that identifying lineage-specific gene loss after genome duplication is important for understanding the evolution of gene subfunctions in surviving paralogs and for improving functional connectivity among human and model organism genomes. We examine the general principles of gene loss following duplication, coupled with expression analysis of the retinaldehyde dehydrogenase Aldh1a gene family during retinoic acid signaling in eye development as a case study. Humans have three ALDH1A genes, but teleosts have just one or two. We used comparative genomics and conserved syntenies to identify loss of ohnologs (paralogs derived from genome duplication) and to clarify uncertain phylogenies. Analysis showed that Aldh1a1 and Aldh1a2 form a clade that is sister to Aldh1a3-related genes. Genome comparisons showed secondarily loss of aldh1a1 in teleosts, revealing that Aldh1a1 is not a tetrapod innovation and that aldh1a3 was recently lost in medaka, making it the first known vertebrate with a single aldh1a gene. Interestingly, results revealed asymmetric distribution of surviving ohnologs between co-orthologous teleost chromosome segments, suggesting that local genome architecture can influence ohnolog survival. We propose a model that reconstructs the chromosomal history of the Aldh1a family in the ancestral vertebrate genome, coupled with the evolution of gene functions in surviving Aldh1a ohnologs after R1, R2, and R3 genome duplications. Results provide evidence for early subfunctionalization and late subfunction-partitioning and suggest a mechanistic model based on altered regulation leading to heterochronic gene expression to explain the acquisition or modification of subfunctions by surviving ohnologs that preserve unaltered ancestral developmental programs in the face of gene loss.     

<Emphasis Type="Italic">Malassezia</Emphasis> spp. in Acoustic Meatus of Bats (<Emphasis Type="Italic">Molossus molossus</Emphasis>) of the Amazon Region,Brazil

The yeasts of the Malassezia genus are opportunistic microorganisms and can cause human and animal infections. They are commonly isolated from the skin and auricular canal of mammalians, mainly dogs and cats. The present study was aimed to isolate Malassezia spp. from the acoustic meatus of bats (Molossus molossus) in the Montenegro region, “Rondônia”, Brazil. From a total of 30 bats studied Malassezia spp. were isolated in 24 (80%) animals, the breakdown by species being as follows (one Malassezia sp. per bat, N = 24): 15 (62.5%) M. pachydermatis, 5 (20.8%) M. furfur, 3 (12.5%) M. globosa and 1 (4.2%) M. sympodialis. This study establishes a new host and anatomic place for Malassezia spp., as it presents the first report ever of the isolation of this genus of yeasts in the acoustic meatus of bats.     

A Novel,Single Algorithm Approach to Predict Acenocoumarol Dose Based on CYP2C9 and VKORC1 Allele Variants

The identification of CYP2C9 and VKORC1 genes has strongly stimulated the research on pharmacogenetics of coumarins in the last decade. We assessed the combined influence of CYP2C9 *2 and *3, and VKORC1 c.-1639G>A, 497C>G, and 1173C>T variants, on acenocoumarol dosage using a novel algorithm approach, in 193 outpatients who had achieved stable anticoagulation. We constructed an “acenocoumarol-dose genotype score” (AGS, maximum score = 100) based on the number of alleles associated with higher acenocoumarol dosage carried by each subject for each polymorphism. The mean AGS was higher in the high-dose (>28mg/week) compared with the low-dose (<7mg/week) group (mean(SEM) of 84.1±3.4 vs. 62.2±4.8, P = 0.008). An AGS>70 was associated with an increased odds ratio (OR) of requiring high acenocoumarol dosage (OR: 3.347; 95%CI: 1.112–10.075; P = 0.032). In summary, although more research is necessary in other patient cohorts, and this algorithm should be replicated in an independent sample, our data suggest that the AGS algorithm could be used to help discriminating patients requiring high acenocoumarol doses to achieve stable anti-coagulation.