Genetic structure of Tunisian natural carob tree (Ceratonia siliqua L.) populations inferred from RAPD markers

? Seven RAPD markers were used to assess the genetic diversity and structure of ten Tunisian natural Ceratonia siliqua L. populations from different geographic and bioclimatic zones.

? The species maintain a high diversity within population as estimated by the percentage of polymorphic loci and Shannon’s index (P% = 76.31, $\bar H'_{pop} = 0.569$ ). The range of variation between populations was large. Populations from the upper semi-arid bioclimates, with more continuous distribution area showed the highest level of variation.

? A high genetic differentiation among populations (Φ_ST = 0.250 and $\bar G_{ST} = 0.347$ ), as a result of population isolation was revealed. Nevertheless, the genetic structure is in accordance with bioclimate indicating that ecological factors also should influence differentiation. Populations from the sub-humid, upper semi-arid and mean semi-arid zones clustered together and were distinct from those of the lower semi-arid ones.

? Conservation strategy should be made according to the level of polymorphism within population and bioclimate.

     

Institutional entrepreneurship and the negotiation and blending of multiple logics in the Southern Arizona local food system

In this paper, we explore the entrepreneurial leadership strategies and routine work of actors located across a diverse array of organizational settings (i.e., farmers’ markets, community farms, community-supported agriculture programs, food and seed banks, local food print media) that combine to shape and sustain the Southern Arizona (AZ) local food system (LFS). We use the theoretical principles of institutional entrepreneurship and logic multiplicity to show how the strategies and routine work of local food actors at the organizational level combine to negotiate system-level meaning and structure within and across the Southern AZ LFS, which is an otherwise seemingly fragmented and contentious social space. We illustrate how the entrepreneurial work performed within multiple organizations and organizational types converge to form a hybrid (or blended) local food logic. Implications are discussed and recommendations for practice are proposed.     

Seed and juice characterization of pomegranate fruits grown in Tunisia: Comparison between sour and sweet cultivars revealed interesting properties for prospective industrial applications

Tunisian pomegranate genetic resources consist of sweet and sour cultivars, showing large morphometric variability. In the present work we characterized seeds and juice contents of sugars and organic acids of 5 sour and 7 sweet pomegranate cultivars. Results showed that citric acid was predominant in sour pomegranates, while malic acid was the most prevalent in sweet ones. Paradoxically, sour cultivars have higher sugar content than the sweet ones. A strong correlation was found between sourness and citric acid content, which is assumed to be the major factor that determines sour taste in pomegranate fruits. Besides, some of the seed parameters showed a significant positive correlation with acidity. Sweet cultivars were appropriate for fresh consumption and juice production due to several attributes in addition to their sweetness. Equally, sour pomegranate showed several characteristics that could be of great interest for food and nutraceutical industries.     

Assessment of diagnostics and antimicrobial susceptibility testing of Brachyspira species using a ring test

There is no ring test for quality assessment available in Europe for diagnostics and antimicrobial susceptibility testing of the fastidious, anaerobic bacteria of the genus Brachyspira. Therefore, an international ring test for Brachyspira spp. was performed once a year during 2002-2004. Two sets of coded samples were prepared and distributed on each occasion. One set comprised six swabs dipped in pig faeces spiked with Brachyspira spp. intended for diagnostics. The other set comprised two pure strains intended only for susceptibility testing. All methods used were in-house methods. The species used were Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira innocens, Brachyspira murdochii and Brachyspira intermedia. In most cases, the correct Brachyspira spp. were detected. However, the results showed that Brachyspira spp. could be difficult to identify, especially if two Brachyspira spp. were mixed or if the concentration of Brachyspira in faeces was low. Additionally, some laboratories reported Brachyspira growth in control samples that were not seeded with any spirochaetes. The lowest detection level was 10(2) bacteria/ml faeces for both B. hyodysenteriae and B. pilosicoli. The susceptibility tests performed showed that disc diffusion was not recommendable for Brachyspira spp. Extended antimicrobial dilution series gave most congruent results. The diversity of the results highlights the importance of ring tests for a high quality of diagnostics and antimicrobial susceptibility tests for Brachyspira spp. This is the first ring test described for Brachyspira spp.     

Genetic diversity in local Tunisian pears (Pyrus communis L.) studied with SSR markers

Few records are available about local Tunisian pear cultivars characterized by low chilling requirements and adaptation to dry conditions. In this work, seven SSRs derived from apple were successfully transferred to 25 local Tunisian pear genotypes and 6 common varieties of Pyrus communis cultivated in Europe. The 7 SSRs used amplified a total of 36 fragments. All the microsatellites except one seem to amplify more than one locus in some of the genotypes studied. Only 12 different fingerprinting patterns could be distinguished among the 25 Tunisian cultivars studied indicating a high number of synonymies. The mean expected and observed heterozygosities in the 25 Tunisian cultivars analyzed averaged 0.71 indicating a high level of genetic diversity among the local Tunisian pear germplasm. These markers will be useful to optimize the conservation of this highly threatened germplasm.     

Characterization of Tunisian pomegranate (Punica granatum L.) cultivars using amplified fragment length polymorphism analysis

The amplified fragment length polymorphism (AFLP) analysis of DNA was used to characterize 34 pomegranate cultivars. By using a combination of six primers, a total of 327 markers were scored with a mean of 57.5. The high percentage of polymorphic bands (ppb) of 94.7 and the resolving power (R_p) collective rate value of 129.14 were scored. Data proved that the tested primers were informative to discriminate among cultivars and to survey the genetic diversity in this fruit crop. It has been assumed that the local pomegranate germplasm is characterized by a typically continuous genetic diversity. The derived dendrogram proved that cultivars are clustered independently from their geographical origin and their denomination. In addition, AFLP permitted the generation of a nearly unlimited number of molecular markers that are reliable in differentiating the cultivars and/or the polyclonal varieties.     

Validation of a commercial ELISA for the detection of bluetongue virus (BTV)-specific antibodies in individual milk samples of Dutch dairy cows

A recently developed indirect ELISA for the detection of bluetongue virus (BTV)-specific antibodies in bovine milk samples was compared to that of the routinely used competitive ELISA on serum samples. During the bluetongue outbreak in the Netherlands in 2006, caused by BTV serotype 8, coupled serum and milk samples were obtained from 470 individual cows from 10 BTV-infected farms with an average seroprevalence of 57%. In addition, bulk milk samples of the same farms, and historically BT-negative samples were tested. Compared to the ELISA for sera, the relative specificity and sensitivity of the ELISA for milk samples is 96.5% and 98.9%, respectively when using a S/P% cut-off value of 50% as advised by the manufacturer. The optimal cut-off value was found at S/P% of 90% revealing an optimal specificity (99.0%) combined with an optimal sensitivity (98.1%). Titres in positive individual milk samples ranged from 1 to 2048 with a peak titre of 128. Bulk milk samples contained antibodies with titres ranging from 64 to 512. The ELISA for milk samples was found to be a reliable and robust test. This diagnostic tool is very useful, and may replace the ELISA for serum samples as first choice in order to get insight into the status of lactating individual animals and therewith of the entire herd with respect to BTV infection.     

Comparative Analysis of Genetic Diversity in Two Tunisian Collections of Fig Cultivars Based on Random Amplified Polymorphic DNA and Inter Simple Sequence Repeats Fingerprints

This study characterized the genetic diversity of 18 Tunisian fig cultivars using random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR). Both random and ISSR primers tested generated a total of 116 RAPD and 47 ISSR markers. Considerable genetic variation was observed among fig cultivars sampled from two regional Tunisian collections with an average diversity of 4.57. RAPD and ISSR banding patterns and genetic distances values reflected the high level of diversity among the collections and lower variability between the two collections. The correlation between the RAPD and ISSR similarity matrices computed for the 153 pairwise comparisons among the 18 varieties was lower and significant. An analysis of molecular variance showed that 92% of the total genetic diversity resided within collections, whereas only 8% between collections. The results indicated that in the local fig germ plasm the information provided by RAPD and ISSR is not analogous, most likely as a consequence of the fact that the two classes of markers explore, at least in part, different portions of the genome.     

Neopterin and biopterin as biomarkers of immune system activation associated with castration in piglets

Recent reports have shown that stressful situations may affect the production of unconjugated pterins (neopterin and biopterin). The aim of the study was to investigate the effect of castration on neopterin and biopterin plasma concentrations in piglets, using 2 groups of 12 piglets allocated to castrated and uncastrated (control) groups. Pterin concentrations were determined by HPLC with fluorescence detection. Blood samples were also analzyed for leukocyte profiles and plasma cortisol concentrations. A time × treatment interaction (P < 0.05) was detected for neopterin concentrations, such that neopterin was greater (P < 0.01) at 1 h after surgery in castrated piglets compared with precastration concentrations, and neopterin was greater (P = 0.05) in castrated than in control piglets at 1 h. Castration had no effect on biopterin concentration (P > 0.1). Time effects (P < 0.05) for neutrophil and lymphocyte concentrations and neutrophil-to-lymphocyte ratios were found. A time × treatment interaction (P < 0.01) was detected for plasma cortisol concentrations, such that cortisol was greater (P < 0.01) at 1 and 24 h after surgery in castrated piglets compared with precastration concentrations and was greater (P < 0.01) in castrated than in control piglets at 1 and 24 h. This study showed that castration activated the immune system of piglets as demonstrated by an increase in plasma neopterin concentrations.     

Cyto-nuclear discordance in the genetic relationships among Tunisian fig cultivars (Ficus carica L.): Evidence from non coding trnL–trnF and ITS regions of chloroplast and ribosomal DNAs

Genetic diversity studies were conducted to evaluate intra-specific relationships in Tunisian fig (Ficus: Moraceae) using sequences of the ITS regions of nuclear ribosomal DNA and the chloroplast non-coding region trnL–trnF (trnL intron, and trnL [UAA]–exon–trnF [GAA] intergenic spacer). All data sets suggest that the sequences obtained showed variations either on their lengths or on their nucleotide compositions. The mean size of these nuclear and cytoplasmic non-coding regions is 697.5 and 1035 base pairs for ITS and trnL–trnF chloroplast DNA, respectively. Our results suggest that the substitution rate estimated for the ITS sequences of nuclear DNA is greater than the one unregistered for the non-coding regions of chloroplast DNA. Therefore, chloroplast DNA shows more homoplasy than the nuclear ribosomal DNA. In fact, the consistency (CI) and retention (RI) indexes calculated for nuclear and cytoplasmic DNAs show values of 0.420 and 0.490 for chloroplast DNA and 0.573 and 0.387 for ribosomal DNA, respectively. The nuclear DNA has more resolution of genetic relationships between cultivars. In addition, the result suggests that the cultivars studied are clustered independently from their geographical origin and the male trees did not thoroughly diverge from the common figs. The discordance between chloroplast and the nuclear topology is revealed. The lack of congruence between the two data sets may be a result of hybridization or introgression. Our result showed that the nuclear and cytoplasmic sequences are useful for germplasm discrimination as well as for investigation of patterns of variation in fig.