Rapid prioritization of alien plants for eradication based on climatic suitability and eradication feasibility

Identifying which introduced species have the greatest potential for establishment, spread and impact is critical for prioritizing pre‐ and post‐border control. Using species distribution modelling and existing species locations we assessed the establishment risk based on the climatic suitability areas of 25 plant species listed as eradication targets under South African regulations. To improve confidence, three bioclimatic models were used to predict the potential distribution of each species. This information was combined with the number of localities and the “eradication feasibility syndromes” in a scoring‐categorical system to rank the species. Three management groups were identified. Group “A” includes species with medium‐high establishment risk and higher likelihood to be eradicated, these species should be a priority for eradication. Group “B” includes species with a medium‐low establishment risk but given the low number of known population and the species characteristics, eradication is likely to be feasible. Finally species in group “C” scored a medium‐high establishment risk but the eradication would be difficult due to the high number of known localities. This ranking provides a rapid method to prioritize the management towards the eradication of new potential invasive plant species in the country combining the establishment risk, known number of localities and the inferred eradication success.     

Development of a plant regeneration system based on friable embryogenic callus in the ornamental Alstroemeria

 Stem segments of seedlings from two Alstroemeria breeding lines, cultured on media supplemented with 4 mg/l 2,4-dichlorophenoxyacetic acid and 0.5–1.0 mg/l 6-benzylaminopurine (BA), initiated soft callus, which became compact after subculture on a medium with only 0.5 mg/l BA. Friable embryogenic calli were initiated from compact callus on a medium supplemented with 10 mg/l picloram. Proembryos developed from friable embryogenic calli via embryos into plants after subculture on medium supplemented with 0.1 mg/l BA. The proembryos formed friable embryogenic calli again after culture on medium supplemented with 10 mg/l picloram. The total time needed to regenerate a complete plantlet from friable callus was approximately 6 months. This system for the production of embryogenic material is considered to have valuable applications for genetic transformation in Alstroemeria. Received: 22 April 1999 / Revision received: 16 July 1999 · Accepted: 20 July 1999     

A fractionation procedure of mouse bone marrow cells yielding exclusively pluripotent stem cells and committed progenitors

The cell surface phenotype of pluripotent hemopoietic stem cells (CFU-S) and committed progenitors (CFU-C1, CFU-C2, BFU-E) of mouse bone marrow was analyzed with respect to their binding of wheat germ agglutinin (WGA) and two monoclonal antibodies, anti-GM-1.2 and anti-PGP-1. Stained cells were fractionated on the basis of differences in fluorescence and light scatter intensity using a light-activated cell sorter. The 6% of the cells that bound most WGA and that also had a relatively high forward light scatter (FLS) and low perpendicular light scatter (PLS) contained nearly all stem cells (CFU-S) and progenitors. Anti-GM-1.2 stained only mature myeloid cells, not CFU-S or the in vitro colony-forming cells. Anti-PGP-1 stained all bone marrow cells in varying intensities: lymphoid cells were dull, CFU-S were intermediate, CFU-C2 were brighter, and mature myeloid cells very bright. Enrichment of progenitor cells was performed by a two-step sorting procedure. First, the 6% most WGA-binding cells with high FLS and low PLS were sorted out. A 10-15-fold enrichment of progenitors and CFU-S was obtained. Next, these cells were restained with anti-GM-1.2 or anti-PGP-1 and again fractionated on the FACS. The GM-1.2-negative cells were then another four- to sevenfold more enriched for stem cells and progenitors. Of the cells in this fraction, 95% could be assigned to a colony-forming unit. With anti-PGP-1, CFU-C2 could be partly separated from more early cells such as CFU-S and BFU-E.     

Combination and triple therapy in patients with stable angina pectoris not adequately controlled by optimal β-blocker therapy

In 60 to 80% of patients with stable angina pectoris at low risk for future coronary events, monotherapy with a β-blocker is an effective treatment. When patients with stable angina pectoris and low risk for events do not respond adequately to optimal β-blocker monotherapy, combination therapy or even triple therapy is may be recommended, but little is known of the actual benefit of such a strategy. We reviewed the evidence from the literature on the effectiveness of combination and triple therapy. Combination therapy with a calcium antagonist or nitrate was found to be more effective than β-blocker monotherapy in the majority of studies, but only an estimated 30% of patients objectively benefit from these combination therapies. Direct comparison shows that combination therapy of a β-blocker with a calcium antagonist is more effective than the combination of a β-blocker with a nitrate. An inadequate response to β-blocker monotherapy is more effectively improved by addition of a calcium antagonist than by alternative use of a calcium antagonist. The use of triple therapy is controversial and not recommended in patients with mild angina pectoris, while for patients with severe angina pectoris not responding to combination therapy of a β-blocker with a nitrate, triple therapy may be of advantage, although the number of patients studied has been small.     

Monoclonal antibodies against human beta-glucocerebrosidase

Monoclonal antibodies were obtained against the membrane-bound lysosomal enzyme beta-glucocerebrosidase (acid beta-glucosidase), which is deficient in Gaucher's disease. BALB/c mice were immunized with homogeneous enzyme protein extracted from a sodium dodecyl sulphate/polyacrylamide gel. The mice were subsequently hyperimmunized with partially purified enzyme prior to fusion of spleen cells with myeloma cells. After fusion, 32 primary hybrid cell populations were obtained which continued to produce antibodies against beta-glucocerebrosidase after prolonged time of culture. All antibodies reacted with both native and denatured enzyme. Four primary cell populations were subcloned and the antibodies produced were characterized. The antibodies were all four of the IgG1 subclass. Three of these antibodies bind to protein A whereas one does not. The results of binding assays indicated that three of the antibodies react with the same antigenic domain (epitope 1), but the fourth with a different one (epitope 2). Probably two antigenic determinants are present in epitope 1 since one of the antibodies with specificity for epitope 1 is inactivated after iodination by the chloramine-T procedure whereas a second one is not.     

Phenological sensitivity to climate change is higher in resident than in migrant bird populations among European cavity breeders

Many organisms adjust their reproductive phenology in response to climate change, but phenological sensitivity to temperature may vary between species. For example, resident and migratory birds have vastly different annual cycles, which can cause differential temperature sensitivity at the breeding grounds, and may affect competitive dynamics. Currently, however, adjustment to climate change in resident and migratory birds have been studied separately or at relatively small geographical scales with varying time series durations and methodologies. Here, we studied differential effects of temperature on resident and migratory birds using the mean egg laying initiation dates from 10 European nest box schemes between 1991 and 2015 that had data on at least one resident tit species and at least one migratory flycatcher species. We found that both tits and flycatchers advanced laying in response to spring warming, but resident tit populations advanced more strongly in relation to temperature increases than migratory flycatchers. These different temperature responses have already led to a divergence in laying dates between tits and flycatchers of on average 0.94 days per decade over the current study period. Interestingly, this divergence was stronger at lower latitudes where the interval between tit and flycatcher phenology is smaller and winter conditions can be considered more favorable for resident birds. This could indicate that phenological adjustment to climate change by flycatchers is increasingly hampered by competition with resident species. Indeed, we found that tit laying date had an additional effect on flycatcher laying date after controlling for temperature, and this effect was strongest in areas with the shortest interval between both species groups. Combined, our results suggest that the differential effect of climate change on species groups with overlapping breeding ecology affects the phenological interval between them, potentially affecting interspecific interactions.     

Natural variation of submergence tolerance among Arabidopsis thaliana accessions

? The exploitation of natural variation in Arabidopsis thaliana (Arabidopsis) provides a huge potential for the identification of the molecular mechanisms underlying this variation as a result of the availability of a vast array of genetic and genomic resources for this species. Eighty-six Arabidopsis accessions were screened for natural variation in flooding tolerance. This forms the first step towards the identification and characterization of the role of candidate genes contributing to flooding tolerance. ? Arabidopsis accessions at the 10-leaf stage were subjected to complete submergence in the dark. Survival curves were plotted to estimate median lethal times as a measure of tolerance. Flooding-associated survival parameters, such as root and shoot oxygen content, initial carbohydrate content and petiole elongation under water, were also measured. ? There was a significant variation in submergence tolerance among Arabidopsis accessions. However, the order of tolerance did not correlate with root and shoot oxygen content or initial amounts of shoot starch and total soluble sugars. A negative correlation was observed between submergence tolerance and underwater petiole elongation. ? Arabidopsis accessions show considerable variation in the ability to tolerate complete submergence, making it a good species in which to identify and characterize genes and to study mechanisms that contribute to survival under water.     

Identification of agronomically important QTL in tetraploid potato cultivars using a marker–trait association analysis

Key message

Nineteen tuber quality traits in potato were phenotyped in 205 cultivars and 299 breeder clones. Association analysis using 3364 AFLP loci and 653 SSR-alleles identified QTL for these traits.

Abstract

Two association mapping panels were analysed for marker–trait associations to identify quantitative trait loci (QTL). The first panel comprised 205 historical and contemporary tetraploid potato cultivars that were phenotyped in field trials at two locations with two replicates (the academic panel). The second panel consisted of 299 potato cultivars and included recent breeds obtained from five Dutch potato breeding companies and reference cultivars (the industrial panel). Phenotypic data for the second panel were collected during subsequent clonal selection generations at the individual breeding companies. QTL were identified for 19 agro-morphological and quality traits. Two association mapping models were used: a baseline model without, and a more advanced model with correction for population structure and genetic relatedness. Correction for population structure and genetic relatedness was performed with a kinship matrix estimated from marker information. The detected QTL partly not only confirmed previous studies, e.g. for tuber shape and frying colour, but also new QTL were found like for after baking darkening and enzymatic browning. Pleiotropic effects could be discerned for several QTL.