Relationship between chloroplast structure and O2 evolution rate of leaf discs in plants from different biotopes in South Finland

Abstract The chloroplast ultrastructure, especially the thylakoid organization, the polypeptide composition of the thylakoid membranes and photosynthetic O₂ evolution rate, chlorophyll (Chl) content and Chi a/b ratio were studied in leaves of nine plants growing in contrasting biotopes in the wild in South Finland. All the measurements were made at the beginning of the period of main growth on leaves approaching full expansion, when the CO₂-saturated O₂ evolution rate (measured at 20°C and 1500 μmol photons m^?2s^?1) was at a maximum, ranging from 19.2 to 6.9 μmol O₂ cm^?2 h^?1. Among the species, the Chi a/b ratio varied between 3.75 and 2.71. In the mesophyll chloroplasts, the ratio of the total length of appressed to non-appressed thylakoid membranes varied between 1.07 and 1.79, the number of partitions per granum varied between 2.8 and 12.0 and the grana area between 21 and 42% of the chloroplast area. There was a significant relationship between the rate of O₂ evolution of the leaf discs and the thylakoid organization in the mesophyll chloroplasts. The higher the O₂ evolution rate, the lower was the ratio of the total length of appressed to non-appressed thylakoid membranes and also the lower the grana area. Although the relationship of the photosynthetic rate with the Chi content and the Chi a/b ratio of the leaves was not as clear, a significant negative correlation existed between the Chi a/b ratio and the ratio of appressed to non-appressed thylakoid membranes, indicating lateral heterogeneity in the distribution of different Chl- protein complexes.     

Redescription of Favella ehrenbergii (Claparède and Lachmann, 1858) Jörgensen, 1924 (Ciliophora: Choreotrichia), with Phylogenetic Analyses Based on Small Subunit rRNA Gene Sequences

ABSTRACT. The identification of Favella ehrenbergii, a marine planktonic ciliate, has largely been based on its lorica features. This approach is potentially problematic given the polymorphic lorica during this organism's life cycle. We isolated a population of F. ehrenbergii from the coastal waters of Incheon, Korea, and revealed its infraciliature using the protargol staining method. Phylogenetic analysis based on small subunit rRNA gene sequences was also performed. Results showed that this population possessed 16 collar membranelles (CM) and about 100 somatic kineties. These features are highly conserved, even in later dividers. As such, the number of CM and somatic kineties can be used as key characteristics for identification of Favella species.     

Correlations between the endothelium-dependent relaxation of the aorta and arterial pressure in rats with myocardial infarction

The effect of experimental myocardial infarction on endothelium-dependent relaxation was studied on isolated rat aorta and compared with the dynamics of arterial pressure (AP). It was shown that the endothelium-dependent relaxation of aorta was increased 1.8 times 3 h following the myocardial infarction. Simultaneously the drop in AP which had begun immediately following the experimental infarction became maximal. In 24 h both the indices were restored practically to the initial level. There was a significant negative correlation between the extent of endothelium-dependent relaxation and AP. It was suggested that the increase in endothelium-dependent relaxation could influence vascular tone, the drop in AP, and, finally, the development of cardiogenic shock in myocardial infarction in man.     

Effects of gentamycin on interactions of neutrophils with Staphylococcus

The authors studied the effect of gentamicin on abilities of neutrophils to uptake and killing of extracellular Staphylococcus. Gentamicin had not changed naturally the ability of healthy men and burn patients neutrophils to uptake Staphylococcus, but intensified the ability of neutrophils to killing of these bacteria.     

Effect of a beta 2-blocker on the adrenergic receptors of lymphocytes in hypertension

A short-term effect of propranolol on beta 2-adrenoceptor density in mononuclear lymphocytes was studied in 15 male patients with essential hypertension. According to receptor density alterations the hypertensive subjects were divided into two groups. In the first group lymphocyte beta 2-receptor density increased substantially (3 times, on the average). Propranolol had a weak antihypertensive effect in this group, with the initially low plasma renin activity remaining unchanged after the treatment. The patients of the second group, on the contrary, revealed features of sympathetic hyperactivity and a decrease (2 times on the average) in lymphocyte beta 2-receptor density. Propranolol administration caused a decline in the initially normal or elevated plasma renin activity as well as in systolic arterial blood pressure and heart rate.     

Morphology and Molecular Phylogeny of Trimyema koreanum n. sp., a Ciliate from the Hypersaline Water of a Solar Saltern

ABSTRACT. A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293‰) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 × 13 μm in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.).     

Impact of leaf damage on growth of mountain birch shoots

Canopies of heterophyllous trees expand by production of long shoots. We have previously shown in mountain birch ( Betula pubescens ssp. czerepanovii ) that damage to internode leaves within long shoots does not impede shoot growth, indicating that long-shoot elongation occurs by means of external resources. To study to what extent leaves other than true long-shoot leaves are necessary for the normal growth of mountain birch long shoots, we simulated herbivore damage to the two basal leaves of shoots (which flush simultaneously with short-shoot leaves) and the short-shoot leaves nearest to the long shoot within the branch. Damage to the two basal long-shoot leaves significantly reduced long-shoot growth. Additional damage to short-shoot leaves, situated proximally to the long shoot, did not retard long-shoot growth any more than damage to basal leaves alone. To determine the extent to which short-shoot leaves within a large branch are responsible for the pooled long-shoot production of the branch, we clipped differing proportions of short-shoot leaves from such branches. We found small but significant reduction in the pooled length of the long shoots of the branch, presumably indicating a limited role in long-shoot elongation of current photosynthates within the branch. Our experiments indicate that long shoots are not independent modular units in their carbon economy.     

Sugar transport together with environmental conditions controls time lags between xylem and stem diameter changes

In the present study the seasonal patterns of time lags between diurnal xylem and whole stem diameter variations at the top and at the base of two Scots pine trees (Pinus sylvestris L.) were compared. The diameter variations were measured during the summers of 2001 and 2002. Time lags were determined using the cross‐correlation method. The lags were found to vary in time according to the different stages of growth. At the top the xylem lagged behind the whole stem between the beginning of stem growth and the end of shoot growth in both years. In 2001 the time lags at the base showed a similar behaviour during stem growth. That kind of seasonal pattern of the time lags would result from the changes in the sink strength due to changing growth rate at different parts of the tree and the differences in the annual rhythm of growth and water availability in the soil (based on precipitation measurements) between the years 2001 and 2002 were reflected in the patterns. The time lags of shrinking and swelling periods during high and low photosynthetic activity (measured using a shoot chamber) were also compared. It was found, for example, that in 2001 in the middle of the growing season at the top of the tree the whole stem lagged on average 15 min more behind the xylem on the days of high photosynthetic activity than on the days of low or moderate. These results show for the first time that the transportation of carbohydrates and variable sink activity could be detected during the growing season in field conditions using stem and xylem diameter variation measurements. Furthermore, these results provide evidence of the pressure gradient‐driven flow also in the phloem of gymnosperms.