Use of two grasses for the phytoremediation of aqueous solutions polluted with terbuthylazine

The capacity of two grasses, tall fescue (Festuca arundinacea) and orchardgrass (Dactylis glomerata), to remove terbuthylazine (TBA) from polluted solutions has been assessed in hydroponic cultures. Different TBA concentrations (0.06, 0.31, 0.62, and 1.24 mg/L) were chosen to test the capacity of the two grasses to resist the chemical. Aerial biomass, effective concentrations (to cause reductions of 10, 50, and 90% of plant aerial biomass) and chlorophylls contents of orchardgrass were found to be more affected. Tall fescue was found to be more capable of removing the TBA from the growth media. Furthermore, enzymes involved both in the herbicide detoxification and in the response to herbicide-induced oxidative stress were investigated. Glutathione S-transferase (GST, EC. 2.5.1.18) and ascorbate peroxidase (APX, EC. 1.11.1.11) of tall fescue were found to be unaffected by the chemical. GST and APX levels of orchardgrass were decreased by the treatment. These negative modulations exerted by the TBA on the enzyme of orchardgrass explained its lower capacity to cope with the negative effects of the TBA.     

Bipolar distributions in vascular plants: A review

Bipolar disjunct distributions are a fascinating biogeographic pattern exhibited by about 30 vascular plants, whose populations reach very high latitudes in the northern and southern hemispheres. In this review, we first propose a new framework for the definition of bipolar disjunctions and then reformulate a list of guiding principles to consider how to study bipolar species. Vicariance and convergent evolution hypotheses have been argued to explain the origin of this fragmented distribution pattern, but we show here that they can be rejected for all bipolar species, except for Carex microglochin. Instead, human introduction and dispersal (either direct or by mountain‐hopping)—facilitated by standard and nonstandard vectors—are the most likely explanations for the origin of bipolar plant disjunctions. Successful establishment after dispersal is key for colonization of the disjunct areas and appear to be related to both intrinsic (e.g., self‐compatibility) and extrinsic (mutualistic and antagonistic interactions) characteristics. Most studies on plant bipolar disjunctions have been conducted in Carex (Cyperaceae), the genus of vascular plants with the largest number of bipolar species. We found a predominant north‐to‐south direction of dispersal, with an estimated time of diversification in agreement with major cooling events during the Pliocene and Pleistocene. Bipolar Carex species do not seem to depend on specialized traits for long‐distance dispersal and could have dispersed through one or multiple stochastic events, with birds as the most likely dispersal vector.     

On-chip hybridization kinetics for optimization of gene expression experiments

DNA microarray technology is a powerful tool for getting an overview of gene expression in biological samples. Although the successful use of microarray-based expression analysis was demonstrated in a number of applications, the main problem with this approach is the fact that expression levels deduced from hybridization experiments do not necessarily correlate with RNA concentrations. Moreover oligonucleotide probes corresponding to the same gene can give different hybridization signals. Apart from cross-hybridizations and differential splicing, this could be due to secondary structures of probes or targets. In addition, for low-copy genes, hybridization equilibrium may be reached after hybridization times much longer than the one commonly used (overnight, i.e., 15 h). Thus, hybridization signals could depend on kinetic properties of the probe, which may vary between different oligonucleotide probes immobilized on the same microarray. To validate this hypothesis, on-chip hybridization kinetics and duplex thermostability analysis were performed using oligonucleotide microarrays containing 50-mer probes corresponding to 10 mouse genes. We demonstrate that differences in hybridization kinetics between the probes exist and can influence the interpretation of expression data. In addition, we show that using on-chip hybridization kinetics, quantification of targets is feasible using calibration curves.     

The neuronal EGF-related genes NELL1 and NELL2 are expressed in hemopoietic cells and developmentally regulated in the B lineage

NELL1 and NELL2 (neural epidermal growth factor-like 1 and 2) are recently described members of the epidermal growth factor gene family that have previously been shown to be expressed almost exclusively in brain tissue. Here we demonstrate regulated expression of NELL1 and NELL2 in human hematopoietic cells. Mature NELL1 mRNA is not detected in any normal hemopoietic cell type, although the gene is transcribed during a narrow window of pre-B cell development, and cell lines at the same developmental stage express the NELL1 mRNA. The related NELL2 gene is expressed by all nucleated peripheral blood cells examined (B, T, monocyte, and natural killer cells), but not in any of the bone marrow B lineage cells at earlier stages of development. However, leukemic cell lines corresponding to the same early differentiation stages express abundant NELL2 mRNA. These results suggest normal and possible oncogenic roles for the NELL proteins in hemopoietic cells.     

Adoption options for laboratory animals

Adoption programs can be enormously satisfying for all involved-not least the animals themselves-and constitute an important refinement in humane animal care and use. Most of the potential problems associated with adoption can be minimized with careful thought and planning. The authors describe adoption programs at two large academic campuses, noting differences between direct and indirect programs.