Genetic diversity in Tunisian Crataegus azarolus L. var. aronia L. populations assessed using RAPD markers

? The genetic diversity of nine wild Tunisian Crataegus azarolus var. aronia L. populations from different bioclimates was assessed using RAPD markers.

? Eight selected primers generated a total of 105 bands, 81 of which were polymorphic. Shannon’s index (H′) ranged from 0.222 to 0.278 according to a population with an average of 0.245. The genetic variation within the species (H _SP = 0.423) was relatively low. A high differentiation (G _ST = 0.421) among populations coupled with a low level of gene flow (N _m = 0.472) were observed. The analysis of molecular variance (AMOVA) revealed also significant differentiation among populations (Φ_ST = 0.371), even at a low scale space. The majority of variation occurred within populations (63.31%). The Mantel test performed on genetic (Φ_ST) and geographic distance matrices among population pairs did not reveal an isolation by distance.

? Interpretation of Neighbour-joining tree based on Nei’s and Li’s genetic distance among individuals showed distinct population groupings. The UPGMA dendrogram based on Φ_ST values revealed two population sub-clusters, each including populations from different bioclimates and/or geographic regions.

? The low level of genetic diversity and the high genetic structure of populations resulted from genetic drift caused both by habitat fragmentation and the low size of populations.

? The high differentiation among populations and the similar low level of diversity within populations suggest that in situ conservation should interest all populations. The ex situ conservation should be based on the collection of seeds rather within than among populations because of the maximum of variation was revealed within populations.

     

The influence of omega-3 polyunsaturated fatty acids (omega-3 pufa) on lactobacilli adhesion to the intestinal mucosa and on immunity in gnotobiotic piglets

The effect of application of omega-3 polyunsaturated fatty acids (omega-3 PUFA) on intestinal colonization by Lactobacillus paracasei and on cellular immunity has been investigated in gnotobiotic pigs. The administration of polyunsaturated fatty acids positively affected the adhesion of Lactobacillus paracasei to the jejunal mucosa of gnotobiotic piglets. When compared to the control group, the number of Lactobacillus paracasei adhering to the jejunal mucosa was by 12% higher in piglets of the experimental group (5.10 log 10/cm2 vs. 4.55 log 10/cm2). The respective counts of Lactobacillus paracasei adhering to the ileal and colonic mucosa of 28 day old gnotobiotic piglets reached 4.45 and 5.05 log 10/cm2 in group C and 4.44 and 4.95 log 10/cm2 in group E. Omega-3 PUFA supplementation increased the phagocytic activity of neutrophils by almost 100% on day 28 of life as well as the subpopulations of lymphocytes (CD8) in the peripheral blood of germ-free piglets on day 21 of life. Our results indicate that the action of probiotics in the gut may be modulated by dietary PUFA. The stimulatory effect of PUFA upon adhesion of lactobacilli could be used for enhancing the effectiveness of probiotics in inhibiting digestive tract pathogens.     

Q fever: an overview

Q fever, a zoonosis caused by the gram-negative bacterium Coxiella burnetii, occurs worldwide and affects both humans and animals. Ruminants are considered to be the main source of infection of humans, with the main route of infection being through inhalation of the organism of fine-particle aerosols. Abortion is the main clinical sign in ruminants. During and after abortion, large quantities of the bacterium are shed via the placenta and other vaginal secretions. The bacterium may also be present in faeces and milk. The bacterium can survive for a long time in the environment after shedding and can be spread over long distances. Seroprevalence among cattle is rather high in the Netherlands and in many other countries. Infection is diagnosed by detecting antibodies against the bacterium or the bacterium itself by means of a PCR method. The efficacy of using antibiotics or vaccines for treatment or prevention of the disease in cattle is still unclear and there are currently no effective disease control programmes.     

Genotypic diversity and symbiotic effectiveness of rhizobia isolated from root nodules of Phaseolus vulgaris L. grown in Tunisian soils

 One hundred and sixty isolates of rhizobia were sampled from the root nodules of common bean (Phaseolus vulgaris L.) cultivated in Tunisian soil samples originating from three geographically distinct fields. Plasmid profiling was used as a primary method to rapidly screen the isolates, and then 38 plasmid types were recorded among the 160 isolates. A sample representing the majority of plasmid types was chosen for further characterization by restriction fragment length polymorphism (RFLP) analysis of genomic DNA using chromosomal and symbiotic gene probes, and by their ability to nodulate a potential alternative host, Leucaena leucocephala. One third of the isolates showed a high similarity to Rhizobium gallicum isolated from common bean in France, another third showed the same characteristics as the R. etli-R. leguminosarum group, while the remaining isolates could not be related to any of the five species nodulating bean. When reexamined for nodulation, some of these isolates, showing similarities to R. tropici and Agrobacterium with respect to colony morphology and growth in different media, failed to nodulate their original host. The R. gallicum-like isolates, R. etli-like isolates, and R. leguminosarum-like isolates were recovered from regions where bean is frequently grown, while in fields which had not been cultivated with beans for at least the 10 previous years, solely unrecognized taxa of ineffective isolates were recovered. We detected variations in the symbiotic regions, but certain pSym RFLP patterns for nifH were conserved between Tunisian, French, and Austrian populations of bean rhizobia. Evaluation of symbiotic effectiveness showed that R. gallicum-like isolates and R. etli-like isolates were effective, whereas some R. leguminosarum-like isolates were ineffective. Furthermore, effective isolates were also found among the unrecognized taxa. Received: 10 March 1998     

Diversity of pomegranate (Punica granatum L.) germplasm in Tunisia

Thirty pomegranate (Punica granatum L.) accessions were studied to determine the overall degree of polymorphism and to detect similarities among genotypes. PCA and cluster analysis showed a considerable phenotypic and genetic diversity in the local pomegranate germplasm. Some polyclonal varieties were identified and cases of homonymy were detected. The geographic origin was not a determinant criterion for cultivars clustering. Parameters with high discriminating values were those related to fruit size and color and juice characteristics. Factors affecting pomegranate germplasm diversity are discussed.     

Sequence analysis of the internal transcribed spacers (ITSs) region of the nuclear ribosomal DNA (nrDNA) in fig cultivars (Ficus carica L.)

Sequences of the internal transcribed spacers (ITSs) of nuclear ribosomal DNA (nrDNA) were analysed in a set of Tunisian fig (Ficus carica L.) cultivars. The size of the spacers sequences ranged from 200 to 279 bases for ITS1 and from 253 to 314 bases for ITS2. Variation of GC contents has been also observed and scored as 59–68% and 55–68% for ITS1 and ITS2, respectively. This data exhibited the presence of polymorphism among cultivars. The intra-specific variability level of the ITS sequences proved a variation both in the length and in the sequences studied. In fact, ITS1 and ITS2 sequences were considered as a useful tool to establish genetic relationships among cultivars. Our results indicate that the diversity detected among closely related genotypes supported strongly the efficiency of ITS sequences for establishing relationships between cultivars. ITS2 seems to be relatively more informative than ITS1 regarding length or GC contents. Considerable genetic diversity was observed among fig at intra and inter-cultivars levels. Two polyclonal varieties were identified. In addition, data proved that a typically continuous genetic diversity characterizes the local fig germplasm. The topology of the derived dendrogram strongly supported this assumption. In fact, genotypes are clustered independently from their geographical origin or the sex of trees suggesting a narrow genetic basis among the ecotypes studied in spite of their phenotypic distinctiveness. Implications of these results for management of fig germplasm collections are discussed.     

Poverty and household food security of black South African farm workers: the legacy of social inequalities

OBJECTIVE: To assess socio-economic indicators, nutritional status and living conditions of farm workers and their families, with the purpose to develop research and intervention programmes aimed at enhancing nutritional status and quality of life. DESIGN AND SETTING: Three farm schools in two districts of the North-West Province and farming communities were selected. Anthropometrical measurements, structured face-to-face questionnaires and focus group discussions were carried out in 2002 and 2003 by a multidisciplinary research team. RESULTS: Access to electricity, water and sanitation, as well as monthly food rations or subsidies, vary and depend on farm owners. The majority of adults have education below or up to grade four, farm schools provide only up to grade seven. Distance to farm schools and intra-household issues hamper children's attendance and performance at school. Household food security is compromised due to a lack of financial resources, infrastructure and also household resource allocation. This impacts negatively especially on children, with half of them being underweight, stunted or wasted. Employment is usually linked to men, while most women have access to casual jobs only. Insecurity of residence and the perceived disempowered position towards farm owners add to feelings of hopelessness and stress. CONCLUSIONS AND RECOMMENDATIONS: This study highlights destitute living conditions of farm worker families. Apart from structural and financial constraints, paternalistic structures of the past might also hamper development. Based on these findings, follow-up research projects and in-depth investigations into underlying social issues with regard to nutrition insecurity and livelihoods of farm workers were initiated.     

Diarrhea and loss of production on Dutch dairy farms caused by the Schmallenberg virus

At the end of August and the first two weeks of September 2011 dozens of veterinary practitioners reported to GD Veekijker (Animal Health Service) several dairy herds with cows with sudden decreased milk production, watery diarrhea and sometimes fever. In the beginning these reports came from the Eastern region of the Netherlands, after that also from the other three regions. The percentages of diseased herds per veterinary practice varied from a few till dozens per cent. Extensive bacteriological, virological and parasitological testing of the feces of sick cows did not reveal an infectious cause of the clinical problems. Recently, 50 stored blood samples of clinically diseased cattle were tested for the Schmallenbergvirus using a PCR, and 36% (18/50) tested positive. A large group of control cows (n=115) was also tested with the PCR and all cattle tested negative. Likely the Schmallenbergvirus was the primary cause of the clinical symptoms in the Dutch dairy herds. Further research will be done to confirm this.     

Social network size affects neural circuits in macaques

It has been suggested that variation in brain structure correlates with the sizes of individuals' social networks. Whether variation in social network size causes variation in brain structure, however, is unknown. To address this question, we neuroimaged 23 monkeys that had been living in social groups set to different sizes. Subject comparison revealed that living in larger groups caused increases in gray matter in mid-superior temporal sulcus and rostral prefrontal cortex and increased coupling of activity in frontal and temporal cortex. Social network size, therefore, contributes to changes both in brain structure and function. The changes have potential implications for an animal's success in a social context; gray matter differences in similar areas were also correlated with each animal's dominance within its social network.     

Genetic variation of Tunisian Myrtus communis L. (Myrtaceae) populations assessed by isozymes and RAPDs

The genetic variation of six Tunisian Myrtus communis L. (Myrtaceae) populations was assessed using nine isozymes coding for 17 putative loci and 79 RAPD markers, amplified by five decamer random primers. The analysed populations belonged to three bioclimatic zones (lower humid, sub-humid and upper semi-arid). A high genetic diversity within populations was detected both by isozymes and RAPDs. The level of variation differed according to bioclimate. Populations collected from sub-humid bioclimate showed more polymorphism than those grown in the upper semi-arid zone. For all populations, the genetic diversity revealed by RAPDs was more pronounced than that detected with isozymes. A high differentiation among populations related to bioclimate and geographic distance was revealed by both methods. Population’s structure based on RAPD markers was more concordant with bioclimatic zones in comparison with isozymes. Differentiation between ecological groups was higher than that revealed within groups. Conservation programs should take into account the level of genetic diversity within population revealed by the two complementary classes of markers according to bioclimate.