Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera     

Effect of temperature on the physiology and cytology of the methylotrophic yeastCandida boidinii growing in methanol-limited chemostat

All deviations from optimum cultivation temperature affect strongly the physiology and morphology of cells ofCandida boidinii strain 2 during growth in methanol-limited chemostat. The optimum cultivation temperature was 28–30 °C at which maximum cell concentration and maximum cell yield (Y _S 0.4 g/g) were achieved. At suboptimal growth temperatures the cells were rich in cell protein, RNA, alcohol oxidase (AO) and in peroxisomes. Formation of cubic peroxisomes and a 20 % decrease of budding cells in the population was observed. At supraoptimal growth temperatures (>30 °C) a sharp decrease in AO activity was accompanied by degradation of peroxisomes in the cells. The culture forms pseudomycelium: at 34 °C the cells stop growing and they are washed out of the bioreactor.     

Ecological and methodological drivers of non-stationarity in tree growth response to climate

Radial tree growth is sensitive to environmental conditions, making observed growth increments an important indicator of climate change effects on forest growth. However, unprecedented climate variability could lead to non-stationarity, that is, a decoupling of tree growth responses from climate over time, potentially inducing biases in climate reconstructions and forest growth projections. Little is known about whether and to what extent environmental conditions, species, and model type and resolution affect the occurrence and magnitude of non-stationarity. To systematically assess potential drivers of non-stationarity, we compiled tree-ring width chronologies of two conifer species, Picea abies and Pinus sylvestris, distributed across cold, dry, and mixed climates. We analyzed 147 sites across the Europe including the distribution margins of these species as well as moderate sites. We calibrated four numerical models (linear vs. non-linear, daily vs. monthly resolution) to simulate growth chronologies based on temperature and soil moisture data. Climate–growth models were tested in independent verification periods to quantify their non-stationarity, which was assessed based on bootstrapped transfer function stability tests. The degree of non-stationarity varied between species, site climatic conditions, and models. Chronologies of P. sylvestris showed stronger non-stationarity compared with Picea abies stands with a high degree of stationarity. Sites with mixed climatic signals were most affected by non-stationarity compared with sites sampled at cold and dry species distribution margins. Moreover, linear models with daily resolution exhibited greater non-stationarity compared with monthly-resolved non-linear models. We conclude that non-stationarity in climate–growth responses is a multifactorial phenomenon driven by the interaction of site climatic conditions, tree species, and methodological features of the modeling approach. Given the existence of multiple drivers and the frequent occurrence of non-stationarity, we recommend that temporal non-stationarity rather than stationarity should be considered as the baseline model of climate–growth response for temperate forests.     

Decomposing trends in bird populations: Climate,life histories and habitat affect different aspects of population change

Aim

Despite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.

Location

Czech Republic.

Methods

We used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.

Results

The first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump-shaped and U-shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump-shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.

Main Conclusion

Although habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non-trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.     

Annotated chromosome numbers of selected asiaticPotentilla species

Chromosome numbers are reported for 19 collections representing 16 AsiaticPotentilla taxa. The first chromosome records are reported forP. desertorum Bunge var.arnavatensis Wolf (2n=28),P. festiva Soják (2n=28),P. griffithii Hook f. subsp.beauvaisii (Cardot) Soják (2n=42),P. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják (2n=14),P. mollissima Lehm. (2n=28),P. moorcroftii Wall. exLehm. (2n=42),P. multicaulis Bunge (2n=14),P. [x]omissa Soják (2n=35, 56, 70) andP. stanjukoviczii Ovcz. exKoczk. (2n=14). Counts differing from those previously recorded are given forP. algida Soják (2n=56) andP. flagellaris Willd. exSchlecht. (2n=42). Chromosome numbers of the following species were confirmed:P. [x]agrimonioides Bieb. (2n=42),P. chinensis Ser. in DC. (2n=14),P. fragarioides L. (2n=14),P. lineata Trev. (2n=14) andP. sericea L. (2n=28). Taxonomy is briefly discussed. A new combinationP. micropetala D. Don subsp.byssitecta (Soják) Měsí?ek etSoják stat. nov. is proposed.     

Cultivation of lymphatic cells in protein-free medium and chemical study of the products

Rabbits immunized withBrucella suis within a period of one week formed antibodies in high titres. These antibodies were of a macroglobulin character only. Cells from the spleen and popliteal lymph nodes were cultivatedin vitro in protein-free medium, in which the only macromolecular substance was dextran or carbowax. Physico-chemical analysis of secretion products was not succesful, since under the given cultivation conditions the cells started to disintegrate from the outset and the medium contained nucleic acids as well as proteins. Some of these substances were present in particles of the size of different subcellular particles. After cultivation of spleen and lymph node cells, antibodies were detected by an agglutination test in media containing dextran and carbowax. When particles substantially larger than the antibody molecule were removed by ultracentrifugation, the agglutination antibody titre in the medium fell.     

Antibody binding capacity of different peptide chains isolated from digested and purified horse diphtheria antitoxin

In commercial digested and purified horse diphtheria antitoxin, which is formed largely of the gamma globulin fragment with the sedimentation coefficient 5.3 S, the reactive disulphide bonds were destroyed by S-sulphonation. Gel filtration on Sephadex G-100 in 0.05 M formic acid with 6 M urea showed that the molecule of the S-sulphonated preparation dissociated into chains similar in character to the peptide chains of native horse antitoxins. Antibody activity was still partly maintained even after treatment with 6 M urea. On mixing the two types of chains isolated by gel filtration, antibody activity was recovered, the amount of antibody protein determined in the mixed fractions being greater than the sum of the amounts in the separate fractions. The neutralizing activity of the mixed fractions tested against toxinin vivo was also greater than the sum of the activity of the separate fractions.     

Karyological variation in the group ofMyosotis alpestris (boraginacea)

A total of 6 population samples ofMyosotis stenophylla Knaf, a rare species showing great ecological disjunction in its distribution, were examined to clarify the present status of its karyological variation. In order to elucidate relationships between lowland tetraploid populations ofM. stenophylla and diploid and tetraploid montane populations ofM. alpestris F.W. Schmidt, four population samples ofM. alpestris were also examined. The karyotypes of all populations ofM. alpestris s.l. studied were highly asymmetrical and heterogeneous, being composed of metacentric, submetacentric, subtelocentric and satellited acrocentric chromosomes. The karyotype formula for haploid chromosome set was established: n=x=12=6m+2sm+3st+1t^SAT. Multivariate analysis based on chromosome length and shape showed significant differences between diploid and tetraploid forms ofM. alpestris s.l. Four numerical parameters, used to characterize the karyotype ofM. stenophylla, revealed significant differences between populations on serpentine and on non-serpentine substrates. In addition, the noticeable affinity of the karyotype of non-serpentine populations to that ofM. alpestris tetraploids has been shown by means of discriminant analysis. These data suggest that the unique features of serpentine play an important role in the origin of karyotypic differentiation within populations ofM. stenophylla.