Gene expression changes in response to drought stress in <Emphasis Type="Italic">Citrullus colocynthis</Emphasis>

Citrullus colocynthis (L.) Schrad, closely related to watermelon, is a member of the Cucurbitaceae family. This plant is a drought-tolerant species with a deep root system, widely distributed in the Sahara-Arabian deserts in Africa and the Mediterranean region. cDNA amplified fragment length polymorphism (cDNA-AFLP) was used to study differential gene expression in roots of seedlings in response to a 20% polyethylene glycol-(PEG8000) induced drought stress treatment. Eighteen genes which show similarity to known function genes were confirmed by quantitative relative (RQ) real-time RT-PCR to be differentially regulated. These genes are involved in various abiotic and biotic stress and developmental responses. Dynamic changes with tissue-specific pattern were detected between 0 and 48 h of PEG treatment. In general, the highest induction levels in roots occurred earlier than in shoots, because the highest expression was detected in roots following 4 and 12 h, in shoots following 12 and 48 h of drought. These drought-responsive genes were also affected by the plant hormones abscisic acid (ABA), salicylic acid (SA), or jasmonic acid (JA), indicating an extensive cross-talk between drought and plant hormones. Collectively, these results will be useful to explore the functions of these multiple signal-inducible genes for unveiling the relationship and crosstalk between different signaling pathways.     

Kinematic diversity suggests expanded roles for fly halteres

The halteres of flies are mechanosensory organs that provide information about body rotations during flight. We measured haltere movements in a range of fly taxa during free walking and tethered flight. We find a diversity of wing–haltere phase relationships in flight, with higher variability in more ancient families and less in more derived families. Diverse haltere movements were observed during free walking and were correlated with phylogeny. We predicted that haltere removal might decrease behavioural performance in those flies that move them during walking and provide evidence that this is the case. Our comparative approach reveals previously unknown diversity in haltere movements and opens the possibility of multiple functional roles for halteres in different fly behaviours.     

Showing up the thermal transconformation of Na–DNA in solution by noise spectrography

Measuring the equivalent noise resistance of Na–DNA solutions in NaCl provides in formation about the free ino atmosphere. In an Arrhenius type diagram, the helix → coil transition is clearly brought Out. A Calculation of the number of free ions in the solution as function of temperature, reveals once more the process of ejection of compensating Na⁺ ions form the macromolecules during the thermal transconformation.     

Evolutionary insight into the Peripatopsis balfouri sensu lato species complex (Onychophora: Peripatopsidae) reveals novel lineages and zoogeographic patterning

Evolutionary relationships in the widely distributed velvet worm Peripatopsis balfouri sensu lato species complex were examined using DNA sequence data, gross and SEM morphology. Sequence data were generated for the COI mtDNA and the 18S rRNA loci and analysed using a Bayesian inference approach, maximum likelihood and maximum parsimony. Phylogenetic analyses of the combined DNA sequence data revealed that Peripatopsis clavigera specimens from the southern Cape (clade 1) was sister to P. balfouri sensu lato specimens from the Cederberg Mountains (clade 2). Within the main P. balfouri sensu lato species complex, three addition clades could be discerned (clades 3, 4 and 5). The obligatory troglobitic species Peripatopsis alba was equidistant between the Cape Peninsula and adjacent interior (clade 3) and the two Boland and Hottentots Holland Mountains (clades 4 and 5). On the Cape Peninsula, P. stelliporata specimens nested among the sympatric P. balfouri sensu lato specimens. The Cape Peninsula specimens were sister to specimens from Jonkershoek site 1, Kogelberg and Simonsberg. Two Boland clades were retrieved, comprising Du Toit's Kloof, Bain's Kloof and Mitchell's Pass and sister (in clade 4) to specimens from the Boland and adjacent Hottentots Holland Mountains in clade 5. These results revealed complex biogeographic patterning in the P. balfouri sensu lato species complex. The presence of sympatric, yet genetically discrete species pairs at six of the sample localities (Du Toit's Kloof, Simonsberg, Jonkershoek sites 1 and 2, Kogelberg and Landroskop) suggests that there is reproductive isolation between the lineages. Divergence time estimations suggest a Miocene/Pliocene/Pleistocene cladogenesis. A taxonomic revision of the P. balfouri sensu lato species complex was undertaken to stabilize the taxonomy. P. clavigera is monophyletic and retained for the southern Cape specimens, P. balfouri sensu stricto is now confined to the Cape Peninsula and adjacent interior, while P. stelliporata is regarded as a junior synonym of the latter taxon, P. alba is endemic to the Wynberg Cave systems on the Cape Peninsula. Three novel species (Peripatopsis cederbergiensis, sp. n., Peripatopsis bolandi sp. n. and Peripatopsis purpureus, sp. n.) are described.