List of publications on human biometeorology in Czechoslovakia (period 1920–1960)

International Journal of Biometeorology -     

Involvement of protein phosphorylation in the sensitivity of photosystem II to strong illumination

Four types of differently phosphorylated hylakoids isolated from field grown spinach ( Spinacia oleracea L.) were tested for the sensitivity of photosystem II (PSII) to photoinactivation. Phosphorylation of light-harvesting II complexes (LHCII) protected PSII electron transfer from photoinhibitory damage, while the phosphorylation of the PSII core polypeptides slightly accelerated the decline of electron transfer during high irradiance treatment. Dephosphorylation of the CP43 apoprotein and PsbH protein by an alkaline phosphatase resulted in an extreme sensitivity of the thylakoids to strong illumination. The PSII photoinactivation of thylakoids with the impaired oxygen-evolving complex was found to be independent of phosphorylation.
The thylakoids of the thermophilic cyanobacterium Synechococcus elongates were used in order to compare the plants with an organism where LHCII complexes are missing and the PSII core proteins are not phosphorylated.     

Genetics of sex determination in flowering plants

Most flowering plant species are hermaphroditic, but a small number of species in most plant families are unisexual (i.e., an individ-ual will produce only male or female gametes). Because species with unisexual flowers have evolved repeatedly from hermaphroditic progenitors, the mechanisms controlling sex determination in flowering plants are extremely diverse. Sex is most strongly determined by genotype in all species but the mechanisms range from a single controlling locus to sex chromosomes bearing several linked locirequired for sex determination. Plant hormones also influence sex expression with variable effects from species to species. Here, we review the genetic control of sex determination from a number of plant species to illustrate the variety of extant mechanisms. We emphasize species that are now used as models to investigate the molecular biology of sex determination. We also present our own investigations of the structure of plant sex chromosomes of white campion (Silene latifolia - Melan-drium album). The cytogenetic basis of sex determination in white campion is similar to mammals in that it has a male-specific Y-chromosome that carries dominant male determining genes. If one copy of this chromosome is in the genome, the plant is male. Otherwise it is female. Like mammalian Y-chromosomes, the white campion Y-chromosome is rich in repetitive DNA. We isolated repetitive sequences from microdissected Y-chromosomes of white campion to study the distribution of homologous repeated sequences on the Y-chromosome and the other chromosomes. We found the Y to be especially rich in repetitive sequences that were generally dispersed over all the white campion chromosomes. Despite its repetitive character, the Y-chromosome is mainly euchromatic. This may be due to the relatively recent evolution of the white campion sex chromosomes compared to the sex chromosomes of animals. © 1994 Wiley-Liss, Inc.     

Large old trees increase growth under shifting climatic constraints: Aligning tree longevity and individual growth dynamics in primary mountain spruce forests

In a world of accelerating changes in environmental conditions driving tree growth, tradeoffs between tree growth rate and longevity could curtail the abundance of large old trees (LOTs), with potentially dire consequences for biodiversity and carbon storage. However, the influence of tree-level tradeoffs on forest structure at landscape scales will also depend on disturbances, which shape tree size and age distribution, and on whether LOTs can benefit from improved growing conditions due to climate warming. We analyzed temporal and spatial variation in radial growth patterns from ~5000 Norway spruce (Picea abies [L.] H. Karst) live and dead trees from the Western Carpathian primary spruce forest stands. We applied mixed-linear modeling to quantify the importance of LOT growth histories and stand dynamics (i.e., competition and disturbance factors) on lifespan. Finally, we assessed regional synchronization in radial growth variability over the 20th century, and modeled the effects of stand dynamics and climate on LOTs recent growth trends. Tree age varied considerably among forest stands, implying an important role of disturbance as an age constraint. Slow juvenile growth and longer period of suppressed growth prolonged tree lifespan, while increasing disturbance severity and shorter time since last disturbance decreased it. The highest age was not achieved only by trees with continuous slow growth, but those with slow juvenile growth followed by subsequent growth releases. Growth trend analysis demonstrated an increase in absolute growth rates in response to climate warming, with late summer temperatures driving the recent growth trend. Contrary to our expectation that LOTs would eventually exhibit declining growth rates, the oldest LOTs (>400 years) continuously increase growth throughout their lives, indicating a high phenotypic plasticity of LOTs for increasing biomass, and a strong carbon sink role of primary spruce forests under rising temperatures, intensifying droughts, and increasing bark beetle outbreaks.     

Developmental control of the heat-shock stress regulon in Streptomyces coelicolor

In the differentiating eubacterium Streptomyces coelicolor , nutritional imbalances activate a developmental programme which involves the heat-shock stress regulon. In liquid batch cultures, the growth curve could be separated into four components: rapid growth 1 (RG1), transition (T), rapid growth 2 (RG2) and stationary (S). Patterns of gene expression in cultures subjected to heat shock in various phases were recorded on two-dimensional gels and analysed using advanced statistical methods. The responses of all heat-shock proteins (HSPs) were highly dependent upon the growth phase, thus demonstrating that the four phases of growth were physiologically distinct. For many HSPs, the levels of thermal induction attained were closely related to growth stage-determined levels of synthesis before heat shock, thus supporting the idea that developmental and thermal induction of this stress regulon have common control elements. Cluster analysis identified five groups of HSPs displaying similar kinetics of heat and developmentally induced synthesis, probably reflecting the influence of major regulatory systems. Methods introduced here to analyse the response of groups of genes to multiple simultaneous stimuli should find broad applications to studies of other prokaryotic and eukaryotic regulons.     

Pituitary corticotropin-inhibiting peptide: Properties and use in study of corticotropin action

The biological properties of the naturally occurring pituitary peptide α_h^7–38-adrenocorticotropin (ACTH) have been investigated. α_h^7–38-ACTH is devoid of steroidogenic activity but inhibits competitively ACTH-induced steroidogenesis in vitro as well as in vivo. The long-term actions of ACTH on normal and tumor adrenal cells in culture are also antagonized by α_h^7–38-ACTH. The apparent K_i for the inhibition of cyclic AMP production by α_h^7–38-ACTH (301 ± 62 nm) was significantly higher than the apparent K_i for the inhibition of corticosterone synthesis (21.6 ± 6.8 nm). Analysis of the inhibition of ACTH-induced steroidogenesis and cyclic AMP production in normal rat adrenocortical cells indicates that two separate receptors may be involved in mediating these responses.     

Evaluation of gas chromatograph packings for the separation of butyric acid from serum-catalyzed hydrolysis of ethyl butyrate

Twelve synthetic and pilot adsorbents of different polarity and varying chemical composition were tested for the separation and quantitative determination of butyric acid from serum-catalyzed hydrolysis of ethyl butyrate. A gas chromatographic procedure with flame ionization detector (fld) using these adsorbents is satisfactory for the separation of butyric acid. The best results were obtained with Spheron SDA, Spheron BD, and Porapak R.