Terpenoid and morphological variability of Pinus quadrifolia and the natural hybridization with Pinus monophylla in the San Jacinto Mountains in California

Monoterpenoids from wood of Pinus quadrifolia and Pinus monophylla from south of the San Jacinto Mountains in southern California were analysed by gas-liquid chromatography (GLC). The number of needles per fascicle, the number of resin canals, and the number of abaxial and adaxial stomatal rows in the needles were determined. Percentages of mycrene, α-pinene, and to a minor extent of camphene, β-pinene, limonene, and β-phellandrene, the above mentioned morphological characteristics and previously obtained data were all used for identification and characterisation of species intermediacy in the San Jacinto area. It was concluded that many P. quadrifolia trees in the mixed Buck Ridge stand and some trees in two pure stands of the same area were hybrids and that sympatric and to a lesser extent allopatric introgression of P. monophylla into P. quadrifolia takes place in the San Jacinto region. Introgression of P. quadrifolia into P. monophylla could not be demonstrated.     

Vegetational changes in a wet meadow complex,South Bohemia,Czech Republic

Directional changes of vegetation in a wet meadow complex are described, comparing phytosociological relevés taken in 1956, 1963, 1984 and 1989, and vegetation maps made in 1956 and 1984. The relevés were located at various distances from the pond shore predominantly reflecting differences in water regime and intensity of farming. The data were elaborated using direct and indirect gradient analyses. Alterations of environmental factors (moisture, nitrogen) were expressed using Ellenberg's indicator values. Over most of the area, the former distinct vegetation mosaic has been replaced by uniform meadows due to intensive farming. The area was eutrophicated and partly drained, clearly shown in Ellenberg's indicator values, in species composition and vegetation pattern. Rapid processes of ruderalization took place. A scheme of successional pathways which finally emerged can be applied to analogous wet meadows in comparable geographical regions and used as a tool for prognoses of successional processes in meadows under human impact. The paper demonstrates ways to exploit earlier phytosociological records.     

Modeling the Role of Negative Cooperativity in Metabolic Regulation and Homeostasis

A significant proportion of enzymes display cooperativity in binding ligand molecules, and such effects have an important impact on metabolic regulation. This is easiest to understand in the case of positive cooperativity. Sharp responses to changes in metabolite concentrations can allow organisms to better respond to environmental changes and maintain metabolic homeostasis. However, despite the fact that negative cooperativity is almost as common as positive, it has been harder to imagine what advantages it provides. Here we use computational models to explore the utility of negative cooperativity in one particular context: that of an inhibitor binding to an enzyme. We identify several factors which may contribute, and show that acting together they can make negative cooperativity advantageous.     

Morphological characteristics of cultured fresh and thawed pericardium cells

The need for selection of the optimal material for the manufacturing of cardio-patches can be resolved by the use of cryostored autologous pericardial tissue. This short communication is a concise fragment of a large-scale research and demonstrates only the efficiency of cell culturing before and after pericardial preservation in the low temperature conditions.     

Comparative mineral and hormonal analyses of wild type and TLS somaclonal variant derived from oil palm (Elaeis guineensis Jacq. var. tenera) tissue culture

Comparative mineral and hormonal analyses were made on tissue culture derived truncated leaf syndrome and wild type oil palm seedlings. Mineral analysis confirmed that Boron, Zinc and chlorophyll levels were significantly lower in truncated leaf syndrome leaves than those of wild type. Hormonal analysis also revealed various cytokinin derivatives such as trans-zeatin, trans-zeatin riboside, trans-zeatin O-glucoside and trans-zeatin riboside 5??mono phosphate were significantly higher in truncated leaf syndrome leaves compared to wild type leaves. Brassinolide level was also significantly higher in truncated leaf syndrome leaves than those of the wild type. These observations suggest that the truncated leaf syndrome abnormality could be associated to high cytokinin and brassinosteroid production which affects the uptake of Boron and Zinc.     

Turtles Are Not Just Walking Stones: Conspicuous Coloration and Sexual Selection in Freshwater Turtles

Turtles are among the most intriguing amniotes but their communication and signaling have rarely been studied. Traditionally, they have been seen as basically just silent armored ‘walking stones’ with complex physiology but no altruism, maternal care, or aesthetic perception. Recently, however, we have witnessed a radical change in the perception of turtle behavioral and cognitive skills. In our study, we start by reviewing some recent findings pertaining to various highly developed behavioral and cognitive patterns with special emphasis on turtles. Then we focus on freshwater turtles and use data about their sexual behavior and size sexual dimorphism (SSD) to test whether conspicuous coloration of the head is in these animals related to sexual processes. We found that absence of aggressive mating behavior is statistically associated with the presence of conspicuous coloration on turtles’ heads. It also seems that while species with female-biased SSD are characterised by conspicuously colored head ornaments, in species with male-biased SSD conspicuous coloration is absent. Unlike large females, males thus seem to be under pressure to develop conspicuous coloration and engage in non-aggressive behavior using signaling to succeed in courtship. And finally, we discuss possible roles of head color patterns in turtle communication during mating.     

A nuclear magnetic resonance study of the glucose metabolism of Hymenolepis diminuta exposed to histamine and serotonin in vitro.

The direct effects of the inflammatory mediators, histamine (HI) and serotonin (SE), on the glucose metabolism of Hymenolepis diminuta in vitro were studied by analyzing the excretory products from culture media, containing D-1-13C-glucose and various concentrations of HI and/or SE, by 1H-nuclear magnetic resonance (n.m.r.) spectroscopy. The results revealed that HI markedly accelerated the glycolysis process by increasing the amount of lactate production. The increased glycolytic activity was reflected in a concentration-dependent increase in glucose uptake. Excretion of acetate was also stimulated by HI. A low concentration of SE significantly increased succinate, acetate and lactate excretions, whereas a high concentration had little effect on lactate production and significantly decreased succinate and acetate excretions. A combination of HI and SE treatment at a low concentration had no significant effect, but at a high concentration showed an additive effect, with an increase in lactate production, a decrease in succinate production and an increase in glucose uptake. Thus this work confirms that HI and SE directly influence, albeit differently, energy metabolism of the tapeworm H. diminuta.     

Tissue factor expression in newt iris coincides with thrombin activation and lens regeneration

Lens regeneration in adult salamanders occurs at the pupillary margin of the mid-dorsal iris where pigmented epithelial cells (PEC) re-enter the cell cycle and transdifferentiate into lens. It is not understood how the injury caused by removal of the lens (lentectomy) in one location is linked to initiating the response in a different spatial location (dorsal iris) and to this particular sector. We propose that the blood provides a link between the localised coagulation and signal transduction pathways that lead to regeneration. A transmembrane protein (tissue factor) is expressed in a striking patch-like domain in the dorsal iris of the newt that localises coagulation specifically to this location, but is not expressed in the axolotl, a related species that does not show thrombin activation after lentectomy and cannot regenerate its lens. Our hypothesis is that tissue factor expression localises the initiation of regeneration through the activation of thrombin and the recruitment of blood cells, leading to local growth factor release. This is the first example of gene expression in a patch of cells that prefigures the location of a regenerative response, and links the immune system with the initiation of a regenerative program.