Tuned in: plant roots use sound to locate water

It was recently suggested that beta diversity can be partitioned into contributions of single sites to overall beta diversity (LCBD) or into contributions of individual species to overall beta diversity (SCBD). We explored the relationships of LCBD and SCBD to site and species characteristics, respectively, in stream insect assemblages. We found that LCBD was mostly explained by variation in species richness, with a negative relationship being detected. SCBD was strongly related to various species characteristics, such as occupancy, abundance, niche position and niche breadth, but was only weakly related to biological traits of species. In particular, occupancy and its quadratic terms showed a very strong unimodal relationship with SCBD, suggesting that intermediate species in terms of site occupancy contribute most to beta diversity. Our findings of unravelling the contributions of sites or species to overall beta diversity are of high importance to community ecology, conservation and bioassessment using stream insect assemblages, and may bear some overall generalities to be found in other organism groups.     

Trans-generational specificity within a cnidarian–algal symbiosis

Ocean warming and other anthropogenic stresses threaten the symbiosis between tropical reef cnidarians and their dinoflagellate endosymbionts (Symbiodinium). Offspring of many cnidarians acquire their algal symbionts from the environment, and such flexibility could allow corals to respond to environmental changes between generations. To investigate the effect of both habitat and host genotype on symbiont acquisition, we transplanted aposymbiotic offspring of the common Caribbean octocoral Briareum asbestinum to (1) an environmentally different habitat that lacked B. asbestinum and (2) an environmentally similar habitat where local adults harbored Symbiodinium phylotypes that differed from parental colonies. Symbiont acquisition and establishment of symbioses over time was followed using a within-clade DNA marker (23S chloroplast rDNA) and a within-phylotype marker (unique alleles at a single microsatellite locus). Early in the symbiosis, B. asbestinum juveniles harbored multiple symbiont phylotypes, regardless of source (parent or site). However, with time (~4 yr), offspring established symbioses with the symbiont phylotype dominant in the parental colonies, regardless of transplant location. Within-phylotype analyses of the symbionts revealed a similar pattern, with offspring acquiring the allelic variant common in symbionts in the parental population regardless of the environment in which the offspring was reared. These data suggest that in this host species, host–symbiont specificity is a genetically determined trait. If this level of specificity is widespread among other symbiotic cnidarians, many cnidarian–algal symbioses may not be able to respond to rapid, climate change-associated environmental changes by means of between-generation switching of symbionts.     

Influence of different counterions on the fluorescent probe-DNA complex.

Studies carried out on both linear and covalently closed DNA have clearly revealed at least two different types of probe-DNA complexes depending on the different experimental procedure adopted, and two main types of binding of the probe have been clearly established and referred to as intercalative and external binding. In order to investigate the influences of the different counterions on the stability of the probe-DNA complex, a set of static fluorimetric measurements were performed in a wide range of concentrations (1 mM to 2 M) of different alkaline-earth chlorides. At low salt concentrations (in the range of millimolar values) no detectable fluorescence intensity changes were evidenced by the use of alkaline salts, but a marked decrease was detected by using alkaline-earth salts. The present work investigates moreover the role played by the different salt, in first place Calcium salts, on the stability of ethidium-DNA complex, by the use of the static fluorimetric titration procedure which is able to discriminate between the two strong and weak binding sites on DNA. Our experimental results have been interpreted in terms of a peculiar Calcium-DNA interaction, involving not only the electrostatic charges of phosphate moiety but also the aromatic rings of the bases, i.e., the intercalation sites on double helix DNA.     

Correlation between serum glutathione reductases and bone densitometry values]

Free radicals, because of their marked chemical activity, have often been found to be involved in many human diseases. Enzymatic antioxidant systems, namely glutathione-reductase, present both in red blood cells and in serum, have been demonstrated to play a key role as free radicals scavengers. The present work has been carried out in order to evaluate the possible role played by free radicals in the demineralization process of the bone matrix. Glutathione-reductase activity, assayed by a slightly modified Horn's method, was related to bone density measurements. All the subjects with reduced densitometric values showed reduced glutathione-reductase levels. Our results seem to support the hypothesis of a strict relationship between low activity of antioxidant systems and demineralization process of the bone, in consequence of enhanced free radical levels.     

Lateral gene transfer between prokaryotes and multicellular eukaryotes: ongoing and significant?

The expansion of genome sequencing projects has produced accumulating evidence for lateral transfer of genes between prokaryotic and eukaryotic genomes. However, it remains controversial whether these genes are of functional importance in their recipient host. Nikoh and Nakabachi, in a recent paper in BMC Biology, take a first step and show that two genes of bacterial origin are highly expressed in the pea aphid Acyrthosiphon pisum. Active gene expression of transferred genes is supported by three other recent studies. Future studies should reveal whether functional proteins are produced and whether and how these are targeted to the appropriate compartment. We argue that the transfer of genes between host and symbiont may occasionally be of great evolutionary importance, particularly in the evolution of the symbiotic interaction itself.     

Autosomal dominant atrial septal defect of ostium secundum type. Report of three families

The authors report on three Sicilian families with 17 individuals (10 females and 7 males) in successive generations affected by atrial septal defect of ostium secundum type (S-ASD) without conduction defect. The anomaly was inherited as an autosomal dominant trait. Cytoplasmic inheritance could be excluded, the anomaly being transmitted also by fathers. Familial S-ASD is probably more frequent than commonly reported since cardiological examination of the relatives is not routinely performed in every case of apparently sporadic ASD.