Activation of lysosomal function during dendritic cell maturation

In response to a variety of stimuli, dendritic cells (DCs) transform from immature cells specialized for antigen capture into mature cells specialized for T cell stimulation. During maturation, the DCs acquire an enhanced capacity to form and accumulate peptide-MHC (major histocompatibility complex) class II complexes. Here we show that a key mechanism responsible for this alteration was the generalized activation of lysosomal function. In immature DCs, internalized antigens were slowly degraded and inefficiently used for peptide loading. Maturation induced activation of the vacuolar proton pump that enhanced lysosomal acidification and antigen proteolysis, facilitating efficient formation of peptide-MHC class II complexes. Lysosomal function in DCs thus appears to be specialized for the developmentally regulated processing of internalized antigens.     

Effects of Lime‐Cooking on Carotenoids Present in Masa and Tortillas Produced from Different Types of Maize

Yellow and white maize kernels, masas, tortillas, and nejayote solids were analyzed in terms of lutein, zeaxanthin, cryptoxanthin, β‐carotene, and lipophilic antioxidant (AOX) capacity. The germplasm analyzed included two normal yellow maize, two high‐carotenoid genotypes, and one white for comparison purposes. In general, the yellow maize required 34% more lime‐cooking time compared with the white counterpart. Lime‐cooking significantly changed the extractability of carotenoids in masa and tortillas. No carotenoids were detected in the steepwater or nejayote. The lipophilic AOX activity increased 280‐fold from kernel to masa, but only 70% was retained in the baked tortillas. When masa was baked into tortillas, less than 10% of the carotenoids were retained because of the high temperatures used during baking. Interestingly, tortillas made with the maize kernels with the highest carotenoid content did not have the highest amount of these phytochemicals. Therefore, maize varieties should be evaluated based on the carotenoid content in finished food products instead of the amounts originally found in raw kernels.     

Elimination of the associated microbial community and bioencapsulation of bacteria in the rotifer Brachionus plicatilis

The bioencapsulation of live bacteria in the rotifer Brachionus plicatilis was determined under monoxenic conditions. The first objective was to evaluate the microbiota of the rotifer during intensive production and to obtain sterile rotifer cultures starting from adult females or amictic eggs using PVP-Iodine, Hydrogen peroxide or antibiotic mixtures. In the rotifers, the proportion of vibrios increased significantly during the mass production, displacing other unidentified marine bacteria. Rotifers, in the absence of culturable bacteria were obtained starting from amictic eggs and using Trimetroprim-sulfametoxasole (Bactrim Roche®) at 10 ml l^–1. The effect of members of Vibrionaceae on the survival and growth rate of rotifers was determined under monoxenic conditions. The survival of rotifers was not affected in the presence of different isolates, while amictic egg formation occurred and the populations increased when the strains Vibrio proteolyticus C279 and Aeromonas media C226 were tested. All isolates were successfully incorporated in the rotifers, since there was no significant difference between the numbers of bioencapsulated cells of different strains of isolates. The results show that it is possible to replace the microbial community in rotifer cultures, started from disinfected amictic eggs, with selected bacterial strains. This could be used as a tool for future studies to reveal the role of specific bacteria on first larval stages of marine fish species.     

Marine extinctions revisited

In recent years, more than 130 extinctions have been estimated to have occurred in the marine realm. Here we review this body of evidence and show that this figure may actually be overestimated by as much as 50%. We argue that previous estimates have not fully taken into account critical uncertainties such as naturally variable geographical distributions, and have misinterpreted documentary evidence. However, current evidence indicates that some sharks, rays and reef‐associated species, although not necessarily geographically restricted, are particularly vulnerable to anthropogenic impacts and now occur in very low numbers. Overestimating extinctions is of concern because it could reduce confidence in the credibility of the ‘extinct’ category in threatened species lists and, ultimately, be used to question the integrity of conservation and management policies. We suggest that when integrating future checklists of marine extinct species, there needs to be a more rigorous use of the terminology of extinction, and participation by specialists in each of the particular taxonomic groups involved.     

Spatio-temporal distribution of mutton snapper and dog snapper spawning aggregations in the South-west Atlantic

1. Sites and periods of spawning aggregations of two important fishery resources, the mutton snapper, Lutjanus analis, and the dog snapper, Lutjanus jocu, were identified and validated along the Brazilian north-east coast (latitude 8–15°S) using exploratory analysis of catch per unit effort (CPUE) data, gonadosomatic index analysis, and gonad histology.
2. The CPUE analysis for both species allowed the identification of outliers and far outliers, representing fisheries with exceptional catches, which were used as proxies of possible aggregation.
3. The presence of pre-spawning and recent spawning signs (hydrated oocytes and post-ovulatory follicles) in the ovary of females caught at sites with recurrent records of high CPUE allowed the validation of spawning activity at those specific sites for each species. All aggregation sites identified in this study were located on the outer shelf, close to the shelf break, a region that has been declared an Ecologically and Biologically Significant Marine Area.
4. Comparison of two subregions showed significant differences in size structure of the fish sampled during landings, suggesting a fishing depletion effect in the north region.
5. For both species, reproduction peaked twice in all regions studied, with a more marked peak during summer. However, spawning activity was observed in almost every month of the year, suggesting that seasonal closures could be more effective if combined with spatial measures.
6. In the northern part of the study range, spawning grounds were found to lie just outside the boundaries of one of Brazil's largest marine protected areas. Inclusion of those grounds in the marine protected area would increase protection of these species and also mean increased protection of an Ecologically and Biologically Significant Marine Area, encompassing mesophotic reefs.
7. The identification of these spawning aggregations sites on the north-east coast of Brazil was conducted in collaboration with local fishers that traditionally use bottom handline. Co-management approaches are suggested in view of the importance of these fishing sites for traditional fishing communities that may also face threats due to encroachment of mobile fleets.

     

Amplified fragment length polymorphism for variety identification and genetic diversity assessment in oleander (Nerium oleander L.)

Oleander is a Mediterranean evergreen shrub found along watercourses, gravelly places and damp slopes. It is grown widely as an ornamental for its abundant and long-lasting flowering as well as its moderate hardiness. Genetic relatedness among 71 accessions, including commercial varieties, different sources of the same varieties, and selections from the wild were investigated using amplified fragment length polymorphism (AFLP). Nine primer combinations yielded a total of 603 bands of which 241 were polymorphic. Genetic similarities among accessions were calculated according to Jaccard's Similarity Index and used to construct a dendrogram based on the unweighted pair group method using arithmetic averages. Our results show that the AFLP technique, which can simultaneously and assay a large number of loci randomly distributed in the genome, is much more informative on the genetic relationship and origin of accessions than the limited number of morphological characters conventionally used for variety discrimination. Up to about 9% molecular genetic differentiation was detected among morphologically indistinguishable provenances of the same variety; this can be partly attributed to scoring error but mainly to somatic variation occurring during vegetative propagation. On the other hand lower genetic distance values were sometimes found among varieties which differ in morphological characters and are thus commercialised with different names. The possibility of considering the amount of genetic variation within a variety as the threshold value for discrimination of initial varieties and essentially derived varieties is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of S‐allele genetic diversity in Sicilian almond germplasm comparing different molecular methods

Italian almond germplasm is characterized by a wide diversity in several growing areas among which Sicily is one of the most important. Analysis with consensus and specific primers and DNA sequencing was performed to investigate S‐RNase genetic diversity and to elucidate the homology rate within a genetic pool of 27 Italian accessions. Interestingly, some of the self‐compatible cultivars did not show the presence of S_f allele. Amplicons from consensus and allele‐specific PCR primers revealed a high level of variability. Sequencing of all the S‐RNase amplicons derived from consensus primers allowed the identification of two new S‐RNase alleles (S₅₁ and S₅₂). Surprisingly, despite the AA replacement mutation, S₅₁ did not exhibit any change of its S‐RNase function. Additionally, several mutations, with no effect on amino acid composition, were detected in the intron and/or in the ORF of four known alleles (S_g, S₁₀, S₃₁ and S₃₅). Genetic variation, regarding point mutations and only detected by sequencing, was revealed among 11 of 27 tested cultivars. The new sources of variability might have an interest for product traceability.     

High antinutrient levels and bruchid resistance of cowpea (Vigna unguiculata) seeds

Summary Seeds of some cowpea varieties, characterized by different degrees of storage pest resistance, were analyzed for inhibitors of the following enzymes: porcine amylase, Bacillus amylase, bovine chymotrypsin and trypsin. A broad variation was observed among samples for all tested inhibitors. Submitting the experimental data to the principal component analysis it has been observed that resistant lines are characterized by high levels of both antitryptic and antiamylasic activity. Moreover a high activity of a single inhibitor class is typical of the bruchid susceptible lines. Hence, breeding for high contents of these protein inhibitors could be an effective way of obtaining lines that are naturally resistant to storage pest attack. The limit of this breeding strategy seems to be the difficulty to reduce the antiamylasic activity before eating.     

Protoplast technology for the breeding of top-fruit trees (Prunus, Pyrus, Malus, Rubus) and woody ornamentals

Summary Until recently, temperate fruit trees and woody ornamentals have been regarded as recalcitrant to biotechnological breeding approaches based on protoplasts. This however should no longer be the case, as procedures are now available, not only for the regeneration of complete plants from protoplasts of various tissues of such species, but also for the exploitation of protoplast technology for their genetic manipulation. This paper will examine the recent advances and state of the art in this domain, with particular attention to the use of protoplast technology as a novel tool in the breeding of rosaceous top-fruit tree species and woody ornamentals. Problems and their solutions within the context of regenerating plants from isolated protoplasts of stone (Prunus spp.), pome (Pyrus spp., Malus spp.) and small (Rubus spp.) fruits, and of several shrubby ornamental genotypes (Lonicera spp., Weigela spp., Forsythia spp., Cotoneaster spp.) will be addressed. Interspecific (Prunus spinosa + Prunus cerasifera) and intergeneric (Forsythia spp. + Syringa spp.) somatic hybridization within this group of species, as well as the use of protoplasts for host/pathogen interaction studies (Pyrus/Erwinia amylovora) will also be discussed.     

Problems related to seed production in the African region

Improved seeds can make a substantial contribution to agricultural productivity in African countries. Seeds are one of the most important sources of innovation, particularly in resource-constrained small farm environments. They carry the genetic potential of the crops, determining the upper limit on yield and, therefore, the ultimate productivity of other inputs. Furthermore, new roles for seeds are rapidly recognized all over the world for the delivery systems of many innovative biotechnological products and as carriers of plant protection chemicals, biologicals and growth regulators. The seed sector development in Africa varies considerably among countries. Rather effective and diversified seed industries have slowly emerged and are operational in a few countries (e.g. Egypt, Kenya, Zimbabwe). In a growing number of other countries (e.g. Malawi, Zambia) the seed production and supply system has developed reasonably well in some areas for some crops. However, in most countries (e.g. Cameroon, Ethiopia, Ghana, Tanzania and Uganda) progress has been very limited in spite of investments and assistance. During the last decade a number of countries have undergone privatisation and/or seed market liberalisation as potential solutions to under-performance in the seed sector. However, it is not certain that this will produce a practical improvement and solve the problems of the poor rural majority of the population. In this paper the main problems related to the seed sector in Africa are discussed together with the possible roles of the private and public sectors in developing and maintaining an efficient and active seed industry. This revised version was published online in July 2006 with corrections to the Cover Date.