Biosynthesis and Contents of Gibberellins in Seeded and Seedless Sweet Orange (<Emphasis Type="Italic">Citrus sinensis</Emphasis> L. Osbeck) Cultivars

In this work, we study the capacity to biosynthesize gibberellins (GA) of ovules (either fertilised or unfertilised), developing seeds and pericarp from fruitlets and their relation with fruit set capacity. Experiments were performed in adult, 12-year-old trees of seeded (Pineapple) and seedless parthenocarpic (Washington navel) sweet orange [Citrus sinensis L. Osbeck] cultivars. The activity of GA20-, GA3- and GA2-oxidases and gibberellin levels were measured in the ovules and pericarp of fruitlets in different development states. The results indicate that ovules are the main sites of gibberellin synthesis in fruitlets during the post-anthesis period. The most intense GA₁ synthesis—coincident with the highest expression of GA20ox2, GA3ox1 and GA2ox1—was detected in the ovules of the seeded cultivar, probably induced by fecundation and associated with low early fruitlet abscission rates. By contrast, the low activity detected in the sterile cultivar appears to be rather developmentally or constitutively regulated. As a fruitlet develops, the GA₁ concentration is augmented in the pericarp in comparison to ovules or developing seeds, and levels therein did not exhibit noticeable differences between varieties. Furthermore, developing seeds from pineapple had higher GA₁ content than the unfertilised abortive ovules from Washington navel. Taken together, data suggest a main role for this hormone in the control of fruitlet abscission, and also demonstrate a function in seed development.     

The levels of natural Nosema spp. infection in Apis mellifera iberiensis brood stages

Nosema ceranae is the most prevalent endoparasite of Apis mellifera iberiensis and it is a major health problem for bees worldwide. The infective capacity of N. ceranae has been demonstrated experimentally in honey bee brood, however no data are available about its prevalence in brood under natural conditions. Thus, brood combs from 10 different hives were analyzed over two consecutive years, taking samples before and after winter. A total of 1433 larvae/pupae were analyzed individually and N. ceranae (3.53%) was the microsporidian most frequently detected, as opposed to Nosema apis (0.42%) which was more frequently detected in conjunction with N. ceranae (0.71%). The active multiplication of both microsporidians was confirmed by the expression (real-time-PCR) of the N. ceranae polar tube protein 3 gene and/or the N. apis RNA polymerase II gene in 24% of the brood samples positive for Nosema spp. Both genes are related to microsporidian multiplication. As such, N. ceranae multiplication was confirmed in 1.06% of the samples, while N. apis multiplication was only observed in co-infections with N. ceranae (0.07%). Brood cells were analyzed for the presence of Nosema spp., as those are the immediate environment where the brood stages develop. The brood samples infected by Nosema spp. were in brood cells in which that microsporidians were not detected, while brood cells positive for N. ceranae hosted brood stages that were not apparently infected, indicating that this is unlikely to be the main pathway of infection. Finally, the colonies with brood infected by N. ceranae showed higher levels (numbers) of infected adult bees, although the differences were not significant before (P = 0.260), during (P = 0.055) or after (P = 0.056) brood sampling. These results show that N. ceranae is a bee parasite ubiquitous to all members of the colony, irrespective of the age of the bee. It is also of veterinary interest and should be considered when studying the epidemiology of the disease.     

Carbonate Precipitation of Bacterial Strains Isolated from Sediments and Seawater: Formation Mechanisms

This article presents a research study on carbonate formation in solid and liquid media by Thalassospira sp., Halomonas sp., Bacillus pumilus, and Pseudomonas grimontii, four bacterial strains isolated from sediments and deep seawater. As part of this study, we analyzed carbonic anhydrase activity, pH, adsorption of calcium and magnesium ions, and total organic and inorganic carbon. The geochemical program PHREEQC was also used to calculate the mineral saturation indexes in all the cultures. The minerals formed were studied with X-ray diffraction, X-ray dispersive energy microanalysis, and scanning electron microscopy. In addition, all four bacterial strains were found to induce carbonate precipitation and to have carbonic anhydrase activity. Sterile control experiments did not precipitate carbonate. In solid M1 and B4 media, all of the strains precipitated magnesium calcite, whereas in the liquid media, they precipitated different percentages of magnesium calcite, aragonite, and monohydrocalcite. In both cases, small amounts of amorphous precipitates were also produced. This article discusses carbonate formation and the possible role played by metabolic activity, bacterial surfaces and carbonic anhydrase in this process. Finally, the results obtained lead to a hypothesis regarding the importance of carbonate precipitation for the survival of bacteria populations in certain habitats.     

Different roles attributed to Cav1 channel subtypes in spontaneous action potential firing and fine tuning of exocytosis in mouse chromaffin cells

This study examines the Cav1 isoforms expressed in mouse chromaffin cells and compares their biophysical properties and roles played in cell excitability and exocytosis. Using immunocytochemical and electrophysiological techniques in mice lacking the Cav1.3α1 subunit (Cav1.3(-/-) ) or the high sensitivity of Cav1.2α1 subunits to dihydropyridines, Cav1.2 and Cav1.3 channels were identified as the only Cav1 channel subtypes expressed in mouse chromaffin cells. Cav1.3 channels were activated at more negative membrane potentials and inactivated more slowly than Cav1.2 channels. Cav1 channels, mainly Cav1.2, control cell excitability by functional coupling to BK channels, revealed by nifedipine blockade of BK channels in wild type (WT) and Cav1.3(-/-) cells (53% and 35%, respectively), and by the identical change in the shape of the spontaneous action potentials elicited by the dihydropyridine in both strains of mice. Cav1.2 channels also play a major role in spontaneous action potential firing, supported by the following evidence: (i) a similar percentage of WT and Cav1.3(-/-) cells fired spontaneous action potentials; (ii) firing frequency did not vary between WT and Cav1.3(-/-) cells; (iii) mostly Cav1.2 channels contributed to the inward current preceding the action potential threshold; and (iv) in the presence of tetrodotoxin, WT or Cav1.3(-/-) cells exhibited spontaneous oscillatory activity, which was fully abolished by nifedipine perfusion. Finally, Cav1.2 and Cav1.3 channels were essential for controlling the exocytotic process at potentials above and below -10 mV, respectively. Our data reveal the key yet differential roles of Cav1.2 and Cav1.3 channels in mediating action potential firing and exocytotic events in the neuroendocrine chromaffin cell.     

Localized IRES-Dependent Translation of ER Chaperone Protein mRNA in Sensory Axons

Transport of neuronal mRNAs into distal nerve terminals and growth cones allows axonal processes to generate proteins autonomous from the cell body. While the mechanisms for targeting mRNAs for transport into axons has received much attention, how specificity is provided to the localized translational apparatus remains largely unknown. In other cellular systems, protein synthesis can be regulated by both cap-dependent and cap-independent mechanisms. The possibility that these mechanisms are used by axons has not been tested. Here, we have used expression constructs encoding axonally targeted bicistronic reporter mRNAs to determine if sensory axons can translate mRNAs through cap-independent mechanisms. Our data show that the well-defined IRES element of encephalomyocarditis virus (EMCV) can drive internal translational initiation of a bicistronic reporter mRNA in distal DRG axons. To test the potential for cap-independent translation of cellular mRNAs, we asked if calreticulin or grp78/BiP mRNA 5'UTRs might have IRES activity in axons. Only grp78/BiP mRNA 5'UTR showed clear IRES activity in axons when placed between the open reading frames of diffusion limited fluorescent reporters. Indeed, calreticulin's 5'UTR provided an excellent control for potential read through by ribosomes, since there was no evidence of internal initiation when this UTR was placed between reporter ORFs in a bicistronic mRNA. This study shows that axons have the capacity to translate through internal ribosome entry sites, but a simple binary choice between cap-dependent and cap-independent translation cannot explain the specificity for translation of individual mRNAs in distal axons.     

The role of seasonality in lettuce consumption: a case study of environmental and social aspects

Background, aim and scope  Considerable debate surrounds the assessment of the environmental impacts and the ethical justification for providing a year-round supply of fresh produce to consumers in the developed countries of northern Europe. Society is seeking environmentally sustainable supply chains which maintain the variety of fresh food on offer throughout the year. This paper compares the environmental impacts of different supply chains providing lettuce all year round to the UK and considers consumers' meanings of—and attitudes to—available options. Lettuce has been selected as a case study as its consumption has grown steadily during the last two decades and the supply chains through cold months are protected cropping in the UK and field cropping in Spain; during warm months, lettuce is sourced from field cropping in the UK. Materials and methods  Data were collected from farms supplying each of these supply chains, and life cycle assessment methodology was used to analyse a range of impacts associated with producing (from plant propagation to harvesting and post-harvest cooling) and delivering 1 kg of lettuce to a UK Regional Distribution Centre (RDC). The downstream stages (i.e. retailing, consumption and waste management) are the same regardless of the origin of the product and were omitted from the comparison. The impacts considered included potential to induce global warming and acidification as well as three inventory indicators (primary energy use, land use and water use). Qualitative data were collected in order to assess the consumer considerations of purchasing lettuce also during winter. Results  Importation of Spanish field-grown lettuce into the UK during winter produced fewer greenhouse gas (GHG) emissions than lettuce produced in UK-protected systems at that time (0.4–0.5 vs. 1.5–3.7 kg CO₂-eq/kg lettuce in RDC). Refrigerated transport to the UK was an important element of the global warming potential associated with Spanish lettuce (42.5% of emissions), whilst energy for heating dominated the results in UK-protected cultivation (84.3% of emissions). Results for acidification were more variable and no overall trends are apparent. Results from qualitative social analysis revealed complex and multidimensional meanings of freshness and suggested that the most striking seasonal variation in vegetable/salad eating was a tendency to consume more salads in the summer and more cooked vegetables in the winter, thus suggesting that in-home consumption alone cannot explain the rise in winter imports of lettuce to the UK. Discussion  UK field-grown lettuce had the lowest overall environmental impact; however, those lettuces are only available in summer, so consumers therefore need to either accept the environmental impacts associated with eating lettuce in the winter or to switch consumption to another food product in the winter. When lettuces were field-grown in Spain and then transported by road to the UK, the overall impacts were similar to the UK field lettuces. The variation within farms of the same country employing different cultivation regimes and practices was bigger than between farms of different countries. Conclusions  This paper has explored the environmental consequences of consuming lettuce year-round in the UK. Whilst recognising the small sample size, the comparative analysis of the different supply chains does suggest that seasonality can be an important variable when defining the best choice of lettuce from an environmental point of view. Recommendations and perspectives  Further studies considering more production sites and product types are required to obtain conclusions whose general validity is clear and for different types of fresh produce. A clear distinction to be made in such studies is whether crops are produced in open fields or under protection. New characterisation methods are needed for environmental impacts derived from the use of key agricultural resources such as land and water. Social studies to investigate consumer preferences and the possibility of moving to more seasonal diets should be an integral part of these studies using samples composed of both urban and rural consumers and using a mixed methodology with both quantitative and qualitative components.

North African influences and potential bias in case-control association studies in the Spanish population

Background

Despite the limited genetic heterogeneity of Spanish populations, substantial evidences support that historical African influences have not affected them uniformly. Accounting for such population differences might be essential to reduce spurious results in association studies of genetic factors with disease. Using ancestry informative markers (AIMs), we aimed to measure the African influences in Spanish populations and to explore whether these might introduce statistical bias in population-based association studies.

Methodology/Principal Findings

We genotyped 93 AIMs in Spanish (from the Canary Islands and the Iberian Peninsula) and Northwest Africans, and conducted population and individual-based clustering analyses along with reference data from the HapMap, HGDP-CEPH, and other sources. We found significant differences for the Northwest African influence among Spanish populations from as low as ≈5% in Spanish from the Iberian Peninsula to as much as ≈17% in Canary Islanders, whereas the sub-Saharan African influence was negligible. Strikingly, the Northwest African ancestry showed a wide inter-individual variation in Canary Islanders ranging from 0% to 96%, reflecting the violent way the Islands were conquered and colonized by the Spanish in the XV century. As a consequence, a comparison of allele frequencies between Spanish samples from the Iberian Peninsula and the Canary Islands evidenced an excess of markers with significant differences. However, the inflation of p-values for the differences was adequately controlled by correcting for genetic ancestry estimates derived from a reduced number of AIMs.

Conclusions/Significance

Although the African influences estimated might be biased due to marker ascertainment, these results confirm that Northwest African genetic footprints are recognizable nowadays in the Spanish populations, particularly in Canary Islanders, and that the uneven African influences existing in these populations might increase the risk for false positives in association studies. Adjusting for population stratification assessed with a few dozen AIMs would be sufficient to control this effect.     

Selection and Characterization of Biofuel-Producing Environmental Bacteria Isolated from Vegetable Oil-Rich Wastes

Fossil fuels are consumed so rapidly that it is expected that the planet resources will be soon exhausted. Therefore, it is imperative to develop alternative and inexpensive new technologies to produce sustainable fuels, for example biodiesel. In addition to hydrolytic and esterification reactions, lipases are capable of performing transesterification reactions useful for the production of biodiesel. However selection of the lipases capable of performing transesterification reactions is not easy and consequently very few biodiesel producing lipases are currently available. In this work we first isolated 1,016 lipolytic microorganisms by a qualitative plate assay. In a second step, lipolytic bacteria were analyzed using a colorimetric assay to detect the transesterification activity. Thirty of the initial lipolytic strains were selected for further characterization. Phylogenetic analysis revealed that 23 of the bacterial isolates were Gram negative and 7 were Gram positive, belonging to different clades. Biofuel production was analyzed and quantified by gas chromatography and revealed that 5 of the isolates produced biofuel with yields higher than 80% at benchtop scale. Chemical and viscosity analysis of the produced biofuel revealed that it differed from biodiesel. This bacterial-derived biofuel does not require any further downstream processing and it can be used directly in engines. The freeze-dried bacterial culture supernatants could be used at least five times for biofuel production without diminishing their activity. Therefore, these 5 isolates represent excellent candidates for testing biofuel production at industrial scale.