A marker-assisted backcross approach for developing submergence-tolerant rice cultivars

Submergence stress regularly affects 15 million hectares or more of rainfed lowland rice areas in South and Southeast Asia. A major QTL on chromosome 9, Sub1, has provided the opportunity to apply marker assisted backcrossing (MAB) to develop submergence tolerant versions of rice cultivars that are widely grown in the region. In the present study, molecular markers that were tightly linked with Sub1, flanking Sub1, and unlinked to Sub1 were used to apply foreground, recombinant, and background selection, respectively, in backcrosses between a submergence-tolerant donor and the widely grown recurrent parent Swarna. By the BC₂F₂ generation a submergence tolerant plant was identified that possessed Swarna type simple sequence repeat (SSR) alleles on all fragments analyzed except the tip segment of rice chromosome 9 that possessed the Sub1 locus. A BC₃F₂ double recombinant plant was identified that was homozygous for all Swarna type alleles except for an approximately 2.3–3.4 Mb region surrounding the Sub1 locus. The results showed that the mega variety Swarna could be efficiently converted to a submergence tolerant variety in three backcross generations, involving a time of two to three years. Polymorphic markers for foreground and recombinant selection were identified for four other mega varieties to develop a wider range of submergence tolerant varieties to meet the needs of farmers in the flood-prone regions. This approach demonstrates the effective use of marker assisted selection for a major QTL in a molecular breeding program. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Updated geographical distribution and ecoepidemiology of the triatomine fauna (Reduviidae: Triatominae) in Colombia

Information concerning triatomine records from provinces and municipalities was accumulated-including data indicating natural infections with trypanosomatides-that has been previously published or reported by Colombian provincial health services and research institutes. Altitude appeared to be the main factor responsible for the distribution of the insects. Illustrations summarize the information provided by the above records. A triatomine fauna classification is presented that corresponds to the eco-epidemiological conditions of the country, considering altitude as the factor determining the geographical distribution of these vectors. Rhodnius prolixus, Triatoma dimidiata, Triatoma maculata and Triatoma venosa are considered the major transmission risk species in Colombia, according to the frequency in which they are reported inside dwellings and peridomiciliary areas. Entomological surveillance providess a necessary tool to reinforce the control strategies for Chagas disease. This also allows the evaluation of transmission risk that the sylvatic triatomines represent in Colombia.     

The Protein-disulfide Isomerase ERp57 Regulates the Steady-state Levels of the Prion Protein

Although the accumulation of a misfolded and protease-resistant form of the prion protein (PrP) is a key event in prion pathogenesis, the cellular factors involved in its folding and quality control are poorly understood. PrP is a glycosylated and disulfide-bonded protein synthesized at the endoplasmic reticulum (ER). The ER foldase ERp57 (also known as Grp58) is highly expressed in the brain of sporadic and infectious forms of prion-related disorders. ERp57 is a disulfide isomerase involved in the folding of a subset of glycoproteins in the ER as part of the calnexin/calreticulin cycle. Here, we show that levels of ERp57 increase mainly in neurons of Creutzfeldt-Jacob patients. Using gain- and loss-of-function approaches in cell culture, we demonstrate that ERp57 expression controls the maturation and total levels of wild-type PrP and mutant forms associated with human disease. In addition, we found that PrP physically interacts with ERp57, and also with the closest family member PDIA1, but not ERp72. Furthermore, we generated a conditional knock-out mouse for ERp57 in the nervous system and detected a reduction in the steady-state levels of the mono- and nonglycosylated forms of PrP in the brain. In contrast, ERp57 transgenic mice showed increased levels of endogenous PrP. Unexpectedly, ERp57 expression did not affect the susceptibility of cells to ER stress in vitro and in vivo. This study identifies ERp57 as a new modulator of PrP levels and may help with understanding the consequences of ERp57 up-regulation observed in human disease.     

Parasitized mates increase infection risk for partners

Individuals can gain fitness benefits and costs through their mates. However, studies on sexual selection have tended to focus on genetic benefits. A potentially widespread cost of pairing with a parasitized mate is that doing so will increase an individual's parasite abundance. Such a cost has been overlooked in systems in which parasites are indirectly transmitted. We manipulated the abundance of the nematode parasite Trichostrongylus tenuis, an indirectly transmitted parasite, within pairs of wild red grouse Lagopus lagopus scoticus in spring. Parasite levels were correlated within pairs before the experiment. We removed parasites from males, females, or both members of the pair and evaluated individual parasite uptake over the subsequent breeding period. At the end of the breeding season, an individual's parasite abundance was greater when its mate had not been initially purged of parasites. This cost appeared to be greater for males. We discuss the implications of our results in relation to the costs that parasites may have on sexual selection processes.     

Resveratrol downregulates Akt/GSK and ERK signalling pathways in OVCAR-3 ovarian cancer cells

Phytochemicals constitute a heterogeneous group of substances with an evident role in human health. Their properties on cancer initiation, promotion and progression are well documented. Particular attention is now devoted to better understand the molecular basis of their anticancer action. In the present work, we studied the effect of resveratrol on the ovarian cancer cell line OVCAR-3 by a proteomic approach. Our findings demonstrate that resveratrol down-regulates the protein cyclin D1 and, in a concentration dependent manner, the phosphorylation levels of protein kinase B (Akt) and glycogen synthase kinase-3β (GSK-3β). The dephosphorylation of these kinases could be responsible for the decreased cyclin D1 levels observed after treatment. We also showed that resveratrol reduces phosphorylation levels of the extracellular signal-regulated kinase (ERK) 1/2. Chemical inhibitors of phosphatidylinositol 3-kinase (PI3K) and ERK both increased the in vitro therapeutic efficacy of resveratrol. Moreover, resveratrol had an inhibitory effect on the AKT phosphorylation in cultured cells derived from the ascites of ovarian cancer patients and in a panel of human cancer cell lines. Thus, resveratrol shows antitumor activity in human ovarian cancer cell lines targeting signalling pathway involved in cell proliferation and drug-resistance.     

OrthoClusterDB: an online platform for synteny blocks

Background  

The recent availability of an expanding collection of genome sequences driven by technological advances has facilitated comparative genomics and in particular the identification of synteny among multiple genomes. However, the development of effective and easy-to-use methods for identifying such conserved gene clusters among multiple genomes–synteny blocks–as well as databases, which host synteny blocks from various groups of species (especially eukaryotes) and also allow users to run synteny-identification programs, lags behind.     

Field site selection: getting it right first time around

The selection of suitable field sites for integrated control of Anopheles mosquitoes using the sterile insect technique (SIT) requires consideration of the full gamut of factors facing most proposed control strategies, but four criteria identify an ideal site: 1) a single malaria vector, 2) an unstructured, relatively low density target population, 3) isolation of the target population and 4) actual or potential malaria incidence. Such a site can exist in a diverse range of situations or can be created. Two contrasting SIT field sites are examined here: the desert-flanked Dongola Reach of the Nile River in Northern State, Sudan, where malaria is endemic, and the island of La Reunion, where autochthonous malaria is rare but risk is persistent. The single malaria-transmitting vector at both sites is Anopheles arabiensis. In Sudan, the target area is a narrow 500 km corridor stretching from the rocky terrain at the Fourth Cataract - just above the new Merowe Dam, to the northernmost edge of the species range, close to Egypt. Vector distribution and temporal changes in density depend on the Nile level, ambient temperature and human activities. On La Reunion, the An. arabiensis population is coastal, limited and divided into three areas by altitude and exposure to the trade winds on the east coast. Mosquito vectors for other diseases are an issue at both sites, but of primary importance on La Reunion due to the recent chikungunya epidemic. The similarities and differences between these two sites in terms of suitability are discussed in the context of area-wide integrated vector management incorporating the SIT.     

Ethical,legal and social aspects of the approach in Sudan

The global malaria situation, especially in Africa, and the problems frequently encountered in chemical control of vectors such as insecticide resistance, emphasize the urgency of research, development and implementation of new vector control technologies that are applicable at regional and local levels. The successful application of the sterile insect technique (SIT) for the control of the New World screwworm Cochliomyia hominivorax and several species of fruit flies has given impetus to the use of this method for suppression or elimination of malaria vectors in some areas of Africa including Northern State of Sudan. The research and development phase of the Northern State feasibility study has been started. Sudanese stakeholders are working side-by-side with the International Atomic Energy Agency in the activities of this important phase. Several ethical, legal and social issues associated with this approach arose during this phase of the project. They need to be seriously considered and handled with care. In this paper, these issues are described, and the current and proposed activities to overcome potential hurdles to ensure success of the project are listed.     

Determination of the absolute configuration of the glucosinolate methyl sulfoxide group reveals a stereospecific biosynthesis of the side chain

Glucosinolates are plant metabolites containing an anionic nitrogeneous thioglucosidic core structure and a structurally diverse amino acid-derived side chain, which after hydrolysis by thioglucohydrolases (myrosinases) afford biological active degradation products such as nitriles and isothiocyanates. Structural diversity in glucosinolates is partially due to enzymatic modifications occurring on the preformed core structure, like the recently described oxidation of sulfides to sulfoxides catalyzed by a flavin monooxygenase identified in Arabidopsis thaliana. The enzyme product, 4-methylsulfinylbutylglucosinolate, bears a chiral sulfoxide group in its side chain. We have analyzed the epimeric purity of 4-methylsulfinylbutylglucosinolate by NMR methods using a chiral lanthanide shift reagent. The absolute configuration of the sulfoxide group has been established by comparing the ¹H NMR spectra of the two sulfoximine diastereomers of natural 4-methylsulfinylbutylglucosinolate. According to our data, 4-methylsulfinylbutylglucosinolate isolated from broccoli and A. thaliana is a pure epimer and its sulfoxide group has the R_S configuration. The product of the A. thaliana flavin monooxygenase has these same properties demonstrating that the enzyme is stereospecific and supporting its involvement in glucosinolate side chain formation.     

Combining geometric morphometrics and genetic analysis to identify species of Opisthonema Gill, 1861 in the eastern Mexican Pacific

Studies focusing on the specific identification of the taxonomic cast within the genus Opisthonema are scarce and contradictory, in spite of this species commercial importance and of the potential ecological impact that fisheries may have on the pelagic ecosystem. In this study, the specific composition of thread herrings Opisthonema (O. bulleri, O. medirastre, and O. libertate) in the southeastern region of the Gulf of California was identified using meristic characters, morphometric data, and mtDNA sequences. In this paper we supported the hypothesis that the commercial catch comprises three evolutionary entities with meristic and morphometric differences. The results were based on the number of ceratobranchial gill rakers, the presence of spicules on the gill rakers, the form of insertion of the gill rakers base onto the ceratobranchial segment, the geometric morphometrics of body shape, and the genetic distances from a fragment of Cytochrome Oxidase Subunit I gene (COI) of mtDNA. Specimens of Pacific thread herring were obtained from landings of the small pelagic fleet at Mazatlan, Sinaloa during 2011–2012. Taxonomic categories were assigned to 1060 individuals according to the measurement of meristic characters. A total of 228 thread herrings O. bulleri, (n = 76), O. medirastre (n = 76), and O. libertate (n = 76) were used in the morphometric analysis, and 25 specimens (O. bulleri n = 8, O. medirastre n = 7, and O. libertate n = 10) were used for genetic comparisons. The morphometric results showed differences among the three groups that had been previously identified using meristic characters, giving support to the existence of three discrete morphotypes. The percentage of sequence divergence of the COI gene supports the existence of three clades. Genetic distances were considerably lower within each clade than between clades. The results of this study provide sufficient evidence for the existence of three Pacific thread herring species in the southern Gulf of California.