ஜர்னல் ஆஃப் பைலோஜெனெடிக்ஸ் & எவல்யூஷனரி பயாலஜி

Background: Natal dispersal is the movement of individuals from their birthplaces to their first breeding locations. Such movements constitute one of the most important events in the life histories of birds and other species and are usually biased such that one sex moves farther and/or more frequently.

Methods: In this study, we compile published data for different dispersal and mass characters for the females and males of 92 bird species from 15 different orders. We use these published data to test the prediction, as derived from species-specific dispersal studies, that sex-biased dispersal is related to body size. Our tests rely on comparative methods and alternative dated trees that directly account for the phylogenetic non-independence of species and the uncertainties in their phylogeny inference.

Results: Our comparative tests support the prediction of a link between sex-biased dispersal and body size. Specifically, we find that larger species have more male-biased dispersal, that the dispersal distance is increasing more rapidly in males than in females, and that the female and male dispersal distances are both positively correlated with their sex-specific body masses.

Conclusions: Sex-biased dispersal is related to body size. However, it remains elusive as to what is the mechanism (i.e., social/behavioral or physiological/energetic) that underlies this link. Still, this link is important, because it highlights the related area of species-specific dispersal as a source of new characters, hypotheses, and approaches for determining the underlying forces of sex-biased dispersal.

Background: Human malaria parasite Plasmodium falciparum is transmitted by several species of Anopheles mosquito. The advancement of drug-resistant parasites and insecticide resistance in mosquito vectors are major hurdles in the malaria control. Alternatively, the manipulation of mosquito immunity is also an ideal way to block Plasmodium development inside the insect host. This approach demands the identification of key mosquito molecules that regulate anti-plasmodial immunity. Our previous findings revealed that the silencing of Anopheles gambiae heme peroxidase 15 (AgHPX15, AGAP013327) induced mosquito innate immunity and drastically suppressed the development of human and rodent malaria parasites. Further, we aim to characterize HPX15 orthologs in Indian malaria vectors and other worldwide-distributed anophelines to understand the novelty of this molecule as a plausible target to block Plasmodium development.

Method: AgHPX15 orthologs were cloned from major Indian malaria vectors A. stephensi and A. culicifacies and their conserve domains were determined by CDD search tool. The sequence homology and phylogenetic relationship of these clones with other heme peroxidases was analysed using Mega5.2 software.

Results and conclusion: We found that A. stephensi AsHPX15 and A. culicifacies AcHPX15 clones are close orthologs of A. gambiae AgHPX15. The phylogenetic relationship of these anopheline HPX15 with other animal and plant heme peroxidases revealed that they form a separate lineage-specific cluster and their orthologs are not found in human, nematodes or other related arthropods such as, Drosophila, Aedes and Culex mosquitoes. However, their putative orthologs are present in 16 other globally distributed anophelines and exhibit a highly conserved amino acids identity in the range of 70-99%. Based on these findings we propose that the anopheline-specific and evolutionary conserved heme peroxidase HPX15 may serve as a unique target for designing transmission-blocking strategies to block Plasmodium-mosquito cycle. These findings will generate new frontiers in the field of malaria research and disease control.

Rice (Oryza sativa L.) is the main staple food for more than half of the world’s population. Improving cooking and eating quality of rice is one of the important objectives of many plant breeding programs. Aroma and cooked kernel elongation are two critical parameters that determine the market value, cooking and eating qualities of rice. The objective of this study was to evaluate the genetic diversity of thirteen (13) Oryza sativa L. populations from Kenyan and Tanzanian. Genetic diversity was determined using 8 simple sequence repeats (SSR) markers. Diversity data was analyzed using POWERMARKER version 3.25 and GENALEX v 6.5 software packages. The number of alleles per locus ranged from 2 to 4 alleles with an average of 3.12 across 8 loci. The polymorphic information content (pic) ranged from 0.2920 (RM 282) to 0.6409 (RM 339) in all loci with an average of 0.4821. Pair-wise genetic dissimilarity coefficients ranged from 0.1125 to 0.9003 with an average of 0.5312. The average gene diversity over all SSR loci for the 13 rice varieties was 0.6036, ranging from 0.3550 to 0.6391. Maximum genetic similarity was observed between Kilombero and Supa, BS 370 and BS 217. Minimum genetic similarity was observed between Kahogo and BS 217. Cluster analysis was used to group varieties by constructing dendrograms based on SSR data and morphological characterization of grains. The dendrogram based on SSR data formed two distinct clusters of the 13 rice varieties. RM 339 and RM 241 were the most informative markers and could be used for differentiating rice varieties from diverse geographical origins. Results obtained from this study demonstrated that use of trait specific SSR markers can be relied upon in diversity studies among diverse and closely related genotypes. RM 339 and RM 241 markers are recommended for use in diversity studies and in quality assurance for grading of rice varieties. Further analysis should be carried out using a larger number of samples and markers to come up a more conclusive report on the discriminating power of microsatellite markers based on rice grain quality traits.

Erpobdella octoculata Linnaeus, 1758 (Hirudinea: Arhynchobdellida: Erpobdellidae) is a very common and morphologically variable macrophagous predators of aquatic invertebrates. Here we determined the complete mitochondrial DNA (mtDNA) sequence of this species, as the first representative of the suborder Erpobdelliformes. This genome is 14,407 bp in length with an A+T content of 71.55%, containing 37 typical animal mitochondrial genes and a non-coding region (NCR). All genes were arranged in the same order as most reported annelid. A remarkable strand bias found for all protein coding genes (PCGs) was positive AT-skew and negative GC-skew. The models of secondary structures for the two rRNA genes of this species were predicted. rrnL consisted of six domains and 46 helices, while three domains and 34 helices for rrnS. The secondary structures of some transfer RNA genes were relatively special. Bayesian phylogenetic and maximum likelihood analyses, based on concatenated nucleotide sequences of 12 PCGs, placed E. octoculata within the suborder Hirudiniformes, and the relationships depicted within that order were not quite in agreement with previous morphological classifications. The complete mtDNA sequence of E. octoculata provides important genetic markers for identification, ecological and evolutionary studies of leeches.