系统发生学与进化生物学杂志

Scelerocarya birrea is an important fruit tree that is widely used by the rural populations in most regions in which it is found, for its fruits, bark, timber and even its roots. The local communities harvest the tree products from the wild with minimal attempts to grow it on-farm. The sustainability of such wild harvests is threatened by agriculture, overgrazing and overexploitation for other purposes. Therefore, the species needs urgent conservation measures in addition to selecting superior germplasm for on-farm tree management that will facilitate ease of species cultivation. This has prompted the International Center for Research in Agroforestry (ICRAF) and partners to collect and manage S. birrea germplasm in field genebanks as the initial step towards the species domestication and conservation. In order to effectively manage germplasm, it is important to establish the collection genetic diversity. Six ISSR markers yielded a total of 76 polymorphic bands across the 257 accessions studied. Percentage of polymorphic loci and observed heterozygosity ranged from 75% to 7.89% and H=0.362 to H=0.043, respectively. The partitioning of genetic diversity found a higher (86% P>0.001) intra-population variation and low inter-population variation, typical of the outcrossing nature of S. birrea. According to Jaccard’s dissimilarity index, the highest genetic distance between accessions was 1.000 and the least genetic distance was 0.000. Neighbour-joining clustering grouped the accessions into three major clusters and twenty probable duplicates were identified, which should be eliminated to cut down the cost of conservation. The results obtained suggest that S. birrea ICRAF field genebank collections have a comparatively rich gene pool and, hence, valuable for conservation of S. birrea. The twenty samples showing duplicates would be good for evaluating performance of this long-lived tree species in both locations.

Sad1/UNC-84 (SUN)-domain proteins are residents of inner nuclear membrane (INM), and share structural features across species. We previously reported a highly conserved C-terminal SUN-domain family protein, designated CaSUN1, in the stress-responsive proteomic landscape of a grain legume, chickpea. In this study, we identified two other chickpea SUN proteins, CaSUN2 and CaSUN3, and performed a comparative analysis of the sequence-structure-function relationship to better understand the diversification of SUN-domain superfamily proteins. Sequence similarity across the species was investigated using multiple sequence alignment, which showed conserved patterns between CaSUN1 and the homologs. Phylogenetic analysis showed that plant SUN-domain proteins are clustered in a unique and distinct group. Using ab-initio approach, a 3D protein structure was generated and further validated using various tools including the Ramachandran plot. The results displayed 90.1% of the Ñ„ and ѱ residues angles in the most favoured regions, suggesting a high-quality structural model for CaSUN1. Model deviation and fluctuation analysis were performed using molecular dynamics (MD) simulation of CaSUN1. The secondary structure analysis of CaSUN revealed a similarity between the structural components shared among them. CaSUN1 revealed two functional domains viz., SUN and muskelin, and the presence of kelch-repeat domain pointed out its putative role in oligomerization, while its binding affinity with different ligands indicates diverse functions. These results would not only give deeper insights into the structure-function relationships within the SUNsuperfamily proteins, but also their putative physiological roles.

Mitochondria are well-defined cytoplasmic organelles of eukaryotic cells, which take part in various cellular metabolic functions, mainly cellular respiration. Several researchers have tried to validate the mechanism of gene transfer between the mitochondria and the cell nucleus. However, some scientific facts show it is very difficult or even impossible for a researcher to confirm DNA transfer process from a living organelle, because mitochondria possess certain specific features that prevent certainty of the DNA transfer process: Such as; dynamicity of mitochondrial organelles, exist in big numbers, can change its location, size and shape, however, gene transfer techniques lack precision. Healthy active mitochondrion has perfect double membranes that sustain its function of keeping in all its constituents. So, most probably the pseudogenes or Numts that are detected in eukaryotic nuclei do not come from living mitochondria rather from aged degraded ones. However, it may come from misplaced DNA segments resulted from any gene transfer process.

Knowledge of spatial and temporal distribution of genetic variability within and between populations is a crucial step for establishing strategies management of stored crops and commodities to assure food safety. The maize weevil, Sitophilus zeamais, is known because of his extraordinary potential for destruction of stored cereals; but little is known about its phylogeography and population structure in Africa in general. This study aimed to determine phylogenic relationships and Phylogeographic structuring of maize weevil populations in West and Central Africa. After alignments and corrections, a total of 112 and 109 samples were used for analysis of Cytochrome B and Cytochrome oxidase I, respectively. The standard indices of genetic diversity, analyses of hierarchical molecular variance (AMOVA), haplotypic network, phylogenetic relationships, demographic tests and Nested Clade Phylogeographic Analysis (NPCA) were computed. Analysis of sequences revealed, with the concatenated matrix, for example, the presence of 30 haplotypes and a high level of haplotype diversity and low nucleotide diversity were observed in West Africa (h = 0.922 ± 0.023; π = 0.0067 ± 0.00116); but these both parameters were twice lower in Central Africa’s populations (h=0.512 ± 0.085; π =0.0034 ± 0.00083). The majority haplotype represented 43% of the overall population and connected West Africa to Central Africa. Maize weevil populations showed a genetic structure but indicated a lack of phylogeographic signal. They also showed that most of molecular variance was due to individual characteristics in a population (~60%); while a proportion of molecular divergence (8-14%) was related to a differentiation between two biogeographical regions in Sub-Saharan Africa. The latters were characterized by the presence of endemic haplotypes as well as common haplotypes. Analysis of mismatch distribution, neutrality tests and Bayesian inferences suggested the existence of 4 to 5 main clusters that had separated themselves from a bottleneck followed by a moderate demographic expansion since Pleistocene period.

Objective: To examine the toxicity level of Sansevieria trifasciata (Asparagaceae) leaves and roots extracts.

Methods: The antimicrobial activity was tested against alkaloid, saponins, tannins, anthraquinones screening by two different methods, the brine shrimp toxicity test and ten-fold serial dilution of the powdered plant material in artificial seawater.

Results: The results showed the presence of cytotoxic principles making it effective therapeutic remedy for treating various infections as it possesses effective of its zone of inhibition (lowest concentration of 35.22 μg/ml to the highest concentration of 44.49 μg/ml) using brine shrimp bioassy of Sansevieria trifasciata roots and leaves extracts.

Conclusion: Thus, the toxic potential of the plant extracts yields greater than the recommended LC50 value and reveals positive linear relationship between the concentrations of the extract to the mortality rate using nauplii. The more concentrated the treatment the higher mortality had resulted.