An exploration of associations between assemblages of aquatic plant morphotypes and channel geomorphological properties within British rivers

Riparian vegetation, particularly trees and shrubs, can play a crucial role in the construction and turnover of fluvial landforms, but aquatic plants may also act as river ecosystem engineers. Macrophyte and environmental data from 467 British river reaches are used to explore associations between aquatic plant morphotypes and the physical characteristics of the reaches. The abundance of five plant morphotypes (mosses, linear-submerged, patch-submerged, linear emergent, branched emergent) is estimated for each river reach. Cluster analysis is applied to the abundances of the five morphotypes across the 467 reaches to identify six typical assemblages or clusters of the morphotypes. These clusters are found to be associated with statistically significantly different values of seven physical variables (altitude, slope, median annual flood discharge, channel width, mean bed sediment size, percentage cover of sand and silt on the river bed, and unit stream power). Associations between the morphotype clusters and combinations of the physical variables are explored using Canonical Correspondence Analysis and standard slope–discharge–sediment calibre–channel style graphs. Several of the morphotype clusters are discriminated by unit stream power and bed sediment size. In particular, morphotype clusters dominated by emergent and submerged macrophytes are associated with granules, sand, and finer bed sediments and are rarely found where unit stream power exceeds 100Wm−2. One cluster characterised by branched emergent species with relatively low cover of submerged morphotypes is confined to sites with unit stream power below 20Wm−2; and another cluster characterised by linear emergents with low cover of submerged morphotypes is associated with particularly extensive, fine bed sediments, suggesting possible smothering of submerged plants. In contrast, mosses reach their highest abundance in two clusters associated with the highest unit stream power and coarsest bed sediments, with the patch-submerged morphotype reaching relatively high abundance in the slightly lower energy cluster of these two. British rivers have been modified over hundreds of years such that the sample of study reaches have predominantly single-thread channels. However, the plotting positions of these reaches on established graphs describing slope–discharge–sediment calibre–channel style associations, illustrates the potential of some of these sites to develop wandering or braided forms and, in lower energy situations, the potential for aquatic plants to trap fine sediments and contribute to landform building and channel change if maintenance (cutting and dredging) of the emergent and submerged morphotypes were reduced

Elevated zinc concentration in zeaxanthin-biofortified sweetcorn kernels compared with a commercial hybrid

A glasshouse experiment was conducted to assess the potential for increasing sweetcorn (Zea mays L. var. rugosa) kernel zinc (Zn) concentration. Uptake of Zn was compared between a standard commercial supersweet variety ‘Hybrix 5’ and a zeaxanthin-biofortified variety ‘High zeaxanthin 103146’. The plants were grown in potted soil culture using a Vertisol soil, and five rates of Zn (0, 0.75, 1.5, 3 and 6 kg Zn ha‑1) applied as ZnSO4.7H2O. Cobs were harvested at the appropriate maturity for sweetcorn eating, three weeks after pollination. On a fresh weight (FW) basis, the kernel Zn concentration in ‘High zeaxanthin 103146’ (7.11±0.21 mg Zn kg‑1) was ca. three times that of ‘Hybrix 5’ (2.57±0.20 mg Zn kg‑1) (p<0.001). The higher Zn concentration of ‘High zeaxanthin 103146’ was also significant in other plants parts, although not to the same extent as in kernel concentration. There was no effect of soil Zn fertilisation within the range of concentrations tested on increasing tissue Zn concentration of any plant part. Interestingly, the pollination of ‘High zeaxanthin 103146’ was generally poorer than ‘Hybrix 5’, resulting in lower kernel numbers per cob. Pollination differences may have contributed to the higher Zn concentration in ’High zeaxanthin 103146’ by reducing inter-kernel competition for Zn transported into the cob. The results show that sweetcorn kernels can potentially accumulate higher Zn concentrations and sweetcorn may be a useful target crop for Zn biofortification, while the lack of a soil Zn fertilisation effect suggests that genetic biofortification may be more effective in achieving elevated Zn concentrations in sweetcorn kernels

Identification and Verification of Differential Display cDNAs Using Gene-Specific Primers and Hybridization Arrays

An accurate and streamlined approach to differential display (DD) band identification and verification is described. To minimize false positives, the strategy avoids the use of impure Northern blot probes obtained from PCR-amplified DD bands. To increase throughput, the cloning of DD bands is replaced by a gene-specific primer approach, and hybridization arrays are used in place of Northern blots. In summary, DD bands obtained with long primers were directly sequenced to allow the design and synthesis of gene-specific primers, which were then used to PCR-amplify homogeneous probes for the verification of expression patterns by hybridization array analysis. Differential expression of 60 of the 63 genes tested was confirmed. Thus, false positives are not inherent to DD. The results demonstrate the power of DD used with hybridization arrays to rapidly generate information on expression patterns of differentially expressed genes

Significant differences in physicochemical properties of human immunoglobulin kappa and lambda CDR3 regions

Antibody variable regions are composed of a heavy and a light chain, and in humans, there are two light chain isotypes: kappa and lambda. Despite their importance in receptor editing, the light chain is often overlooked in the antibody literature, with the focus being on the heavy chain complementarity-determining region (CDR)-H3 region. In this paper, we set out to investigate the physicochemical and structural differences between human kappa and lambda light chain CDR regions. We constructed a dataset containing over 29,000 light chain variable region sequences from IgM-transcribing, newly formed B cells isolated from human bone marrow and peripheral blood. We also used a published human naïve dataset to investigate the CDR-H3 properties of heavy chains paired with kappa and lambda light chains and probed the Protein Data Bank to investigate the structural differences between kappa and lambda antibody CDR regions. We found that kappa and lambda light chains have very different CDR physicochemical and structural properties, whereas the heavy chains with which they are paired do not differ significantly. We also observed that the mean CDR3 N nucleotide addition in the kappa, lambda, and heavy chain gene rearrangements are correlated within donors but can differ between donors. This indicates that terminal deoxynucleotidyl transferase may work with differing efficiencies between different people but the same efficiency in the different classes of immunoglobulin chain within one person. We have observed large differences in the physicochemical and structural properties of kappa and lambda light chain CDR regions. This may reflect different roles in the humoral immune response

CDKs: Taking on a role as mediators of dopaminergic loss in Parkinson's disease

Cyclin-dependent kinases (CDKs) are best characterized for their ability to control cell-cycle progression. However, CDK family members are now known to regulate biological processes outside of the cell cycle, including transcription and neuronal development. Multiple CDKs (both cell cycle and non-cell-cycle related) have been associated with neurological conditions, such as Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD). This review will explore the emerging evidence supporting a role for CDKs in neuronal death, focusing on mechanisms involved in the dopaminergic neurodegeneration of PD. An improved understanding of CDK involvement in cell death signaling could facilitate the development of innovative strategies to halt or slow down the characteristic death processes that are associated with some neurodegenerative conditions