Genetic diversity of natural Tunisian Lavandula multifida L. (Lamiaceae) populations assessed by allozymes and random amplification of polymorphic DNA (RAPD)

We compared the genetic diversity estimated from allozymes and from random amplified polymorphic DNA (RAPDs) in a sample of seven Lavandula multifida L. populations from three bioclimates in Tunisia. Seven isozymes coding for 14 putative loci and 97 RAPD markers, amplified by seven decamer random primers, were used. A high genetic diversity within populations was detected both by isozymes (P = 73.8%; Ap = 2.0 and He = 0.231) and RAPDs (61.86 < P < 80.41% and 0.308 < H < 0.459). The populations from the lower semi-arid bioclimate showed relatively higher polymorphism. A high genetic differentiation among all populations and a limited gene flow at all space scales were detected as a result of habitat fragmentation, low size of populations and genetic drift. However, the level of differentiation among populations revealed by RAPDs (ФST = 0.370; GST = 0.372) was higher than that of allozymes (FST = 0.244). The unweighted pair group method with arithmetic mean (UPGMA) dendrograms based on matrices of FST and ФST were not concordant, and there is no significant correlation between the two data sets. The cluster from allozymes revealed higher separation among most populations. The dendrogram from RAPDs separated populations into three distinct subclusters. The groupings of populations in both dendrograms did not reflect spatial geographic or bioclimatic patterns, indicating particular adaptation of populations to local environments. The dendrogram, based on combined data had led to similar population groupings to that probed by RAPDs. The high differentiation among all populations implies that collection of seeds for ex situ conservation should be done from all populations from all bioclimatic zones even at a low geographic distance.Keywords: Lavandula multifida, genetic diversity, population structure, isozymes, random amplified polymorphic DNA (RAPDs)African Journal of Biotechnology Vol. 12(7), pp. 648-65

Genetic diversity and chemical polymorphism of Tunisian Lavandula multifida L. (Lamiaceae) populations

Eleven Tunisian natural populations of Lavandula multifida L., from different geographic regions and bioclimates, were assessed for their variability using six polymorphic loci and 35 terpenoids. Isozymes were revealed by 13% gel electrophoresis. Volatiles were analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). A high genetic diversity within populations and within ecological groups was revealed by allozymes as a result of both of the outbreeding system of the species and the large size of populations before fragmentation. Cluster constructed using Nei’s genetic distances showed high differentiation between populations. Those belonging to the same bioclimatic zone were not strictly grouped together. Essential oil composition varied among populations. Carvacrol (21.14 to 47.02%), acrylic acid dodecanyl ester (8.96 to 14.06%) and β-Bisabolene (12.96 to 19%) were the main components. Chemical population’s structure, at the ecological group level, based on terpenoids was concordant with that of isozymes. Matrices of Wright’s FST and Euclidean distances were also correlated. Population differentiation performed on combined data yielded similar to that shown using each marker separately. Conservation strategies should take into account the levels of genetic diversity and chemical variation in relation to population and bioclimate.Keywords: Lavandula multifida, Tunisia, natural populations, Isozymes, essential oil, bioclimat

The impact of External Auditing In Enhancing Good internal control Practice: Case Study of Economic Organizations in Algeria.

External audit’s function is an independent unit to ensure the effectiveness and efficiency of internal control in the organization. This function covers the role and responsibilities of external audit, skills, expertise and the independence of the external auditors. This study aims to examine the impact of external auditing in enhancing internal control practice of economic organizations in Algeria. Data analysis method was utilized to test the hypothesis and analyzed by multiple regression test using SPSS Version 22. The primary data was collected using questionnaires distributed to the 100 external auditors (Legal Auditors). The validity and reliability test was implemented before the hypothesis test. The result reveals that independent external auditors and the skills and expertise available to them, have a significant impact on enhancing internal control practices. &nbsp

Tamponnade péricardique révélant un lupus érythémateux systémique au cours d’une leishmaniose viscérale atypique

L'association de leishmaniose viscérale (LV) et lupus érythémateux systémique (LES) est rare et grave. La similitude des signes cliniques peut être responsables de difficultés diagnostiques surtout quand les deux  pathologies se déclarent de façon concomitante. Nous rapportons l'observation d'une malade qui avait présenté une association grave et atypique de LV et LES qui se sont déclarés en même temps. La LV était atypique par l'absence du syndrome tumoral, de la fièvre et la négativité de la sérologie leishmaniose. Le LES jusque là méconnu était révélé par une poussée sévère avec différentes atteintes viscérales. L'évolution était favorable sous amphotéricine-B et corticothérapie. En cas d'association des deux pathologies une surveillance particulière est nécessaire à fin de diagnostiquer à temps une atteinte viscérale grave du LES et démarrer précocement une prise en charge étiologique et symptomatique qui est le seul garant de l'évolution favorable.Key words: Leishmaniose viscérale, lupus érythémateux systémique, association, corticothérapi

Genetic diversity of North African Thymus algeriensis in Tunisia: Population structure and implication for conservation

The genetic diversity within and among nine natural populations of Thymus hirtus Willd. subsp. algeriensis (Boiss. et Reut.) Murb. from different geographical and bioclimatic zones were assessed using Random Amplified Polymorphic DNA data. A total of 154 bands were generated from seven selected primers. 141 bands were polymorphic (P=91.56%). The genetic diversity within a population based on Shannon's index which was high (H' pop=0.307) and varied according to bioclimatic zones. Ahigh genetic differentiation among populations (G ST=0.335 and F{cyrillic} ST=0.296) was revealed, suggesting a population isolation and a low level of gene flow among them. The major proportion of the variation was attributable to individual differences within populations. The genetic structure is in accordance with geography distances. The Neighbour- joining tree based on Nei's and Li's genetic distance among individuals showed that individuals from each population clustered together. The UPGMA dendrogram based on F{cyrillic} ST values revealed three clusters each of them includes populations closuring to their geographical origin. The high genetic structure of populations resulted from genetic drift caused both by the habitat fragmentation and the low size of most populations. The 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.Esta investigación fue financiada por una beca del Ministerio de Investigación, Ciencia y Tecnología y el Instituto Nacional de Ciencias Aplicadas y Tecnología (Beca de Investigación 99 / UR/09-10).Esta investigación fue financiada por una beca del Ministerio de Investigación, Ciencia y Tecnología y el Instituto Nacional de Ciencias Aplicadas y Tecnología (Beca de Investigación 99 / UR/09-10)Peer Reviewe

Genetic variability organisation and gene flow in natural populations of Medicago polymorpha L. prospected in Tunisia

International audienc

Diversité génétique des populations naturelles de Rosmarinus officinalis L. (Lamiaceae) en Tunisie

Rosmarinus officinalis L. is widespread in Central and North-Western Tunisia on sites belonging to sub-humid, semi arid superior and arid superior bioclimatic levels. This plant species reproduces exclusively by vegetative propagation. In all populations, regeneration from seeds is extremely rare because of abortion during nutlets maturation and the low rate of seedling establishment. The habitat destruction linked to human activities (vegetation clearing, overgrazing, over-collecting and oils exploitation) and the rarity of new plants establishment via seeds had led to a decrease in population number and size. Using starch gel electrophoresis, we analyzed the polymorphism of 19 Tunisian natural populations belonging to three bioclimatical stages (sub humid, semi arid superior and arid superior) to determine their genetic diversity and structuring. At ten polymorphic loci, the species maintained high levels of genetic variation within populations, despite its predominant vegetative reproduction and the low rate of seedling establishment. The high genotypical diversity of genets, in the starting population, and the outcrossing breeding system should act in favor of this high genetic variability. An average of 11.3% of the variation resides among populations, indicating a substantial level of interpopulational differentiation. A significant population differentiation was observed within each of the three ecological groups. The level of structuring varied in relationship with the population separation and the quality of sites. Differentiation between continuous groups was lower than that observed for discontiguous ones. Nei’s (1972) genetic distance values between pairs of populations were low (0.005< D< 0.232), particularly between close geographic populations. The UPGMA dendrogram, established through Nei’s genetic distances, exhibited two groups of populations. The first one includes populations of sub humid and semi arid superior. Populations within this group clustered according to their geographical proximity. The second group was represented by the arid superior populations geographically close. The high level of genetic similarities between populations and their high differentiation indicated recent population isolation mainly due to environmental (climatic and edaphic) and human (destruction of intermediate sites) factors. Efforts to preserve populations in situ must be made, particularly for the disturbed ones which had shown particular alleles. Moreover, conservation must rely on multiplication of individuals within each population and rehabilitation of forest, according to the bioclimate, with plant species linked to Rosmary populations. Ex situ conservation could be performed by collecting a high number of individuals within populations that showed particular alleles. These individuals should be multiplied via cuttings in multilocal conservatory parks in relationship with the bioclimate.En Tunisie, les populations naturelles de romarin (Rosmarinus officinalis L.) se développent, essentiellement au centre et au nord-ouest du pays, dans les étages bioclimatiques s’étendant du sub-humide à l’aride supérieur. Cette espèce se reproduit principalement par propagation végétative. Dans toutes les populations, la régénération à partir des graines est extrêmement rare du fait de la production d’un nombre élevé de nucules non viables et du faible taux d’installation des plantules. La destruction des habitats liée aux activités humaines (ouverture du milieu, surpâturage, collecte, distillation des huiles essentielles), associée au faible pouvoir de régénération d’individus à partir de semis, conduisent progressivement à une diminution du nombre et de la taille des populations. Dix-neuf populations de romarin, prospectées dans différents étages bioclimatiques de la Tunisie, ont fait l’objet d’une analyse du polymorphisme de huit systèmes isoenzymatiques afin d’évaluer leur diversité génétique et mesurer le niveau de leur différenciation. Pour les dix loci polymorphes détectés, l’espèce a présenté une diversité génétique intra-population importante, malgré la prédominance de son mode de reproduction végétative et le faible taux d’établissement des plantules. L’importante diversité génétique dans la population d’origine et les modalités de reproduction allogame pourraient expliquer cette variabilité génétique élevée. Une moyenne de 11,3 % de variation est répartie entre les populations ce qui indique un niveau de différenciation important entre les populations. Au sein de chacun des trois groupes écologiques, la différenciation des populations s’est révélée significative. L’éloignement géographique des populations, s’accordant généralement avec leur localisation bioclimatique et le degré de dégradation des habitats, joueraient un rôle important dans cette structuration. La structuration des populations appartenant à des étages bioclimatiques contigus s’est révélée moins importante que celle observée pour les populations se développant dans des étages séparés. Les valeurs des distances génétiques de Nei (1972), pour l’ensemble des paires de populations, se sont révélées être faibles (0,005< D< 0,232), particulièrement entre populations géographiquement proches. Le dendrogramme, établi à partir de ces indices, a montré la formation de deux ensembles réunissant respectivement (i) les populations du sub-humide et du semi-aride supérieur et (ii) les populations de l’aride supérieur. L’agrégation des populations au sein du premier groupe s’opère selon leur proximité géographique. La forte similarité génétique des populations et leur différenciation substantielle témoigneraient d’une récente isolation des populations sous l’influence des facteurs environnementaux (climatiques et édaphiques) et anthropiques (destruction des habitats intermédiaires). La conservation de l’espèce, in situ, doit concerner dans un premier temps les populations présentant des allèles particuliers. Elle doit s’appuyer sur la multiplication d’individus à l’intérieur de chaque population et la restauration de la végétation forestière, selon le bioclimat, par des essences associées normalement au romarin. La conservation ex-situ, pourrait être abordée par la collecte d’un maximum d’individus au sein des populations caractérisées par des allèles particuliers et leur multiplication dans des conservatoires multilocaux au niveau des différents étages bioclimatiques.Zaouali Yosr, Messaoud Chokri, Boussaid Mohamed. Diversité génétique des populations naturelles de Rosmarinus officinalis L. (Lamiaceae) en Tunisie. In: Ecologia mediterranea, tome 29 n°2, 2003. pp. 199-215