Structural and Functional Grounds for Ephedra sinica Expansion in Mongolian Steppe Ecosystems

Morphological and structural characteristics of photosynthetic organs, diurnal changes in photosynthetic and transpiration rates, and the efficiency of water use were studied in three plant species from mountain-steppe ecosystems in Mongolia, Ephedra sinica Stapf, Stipa glareosa P. Smirn., and Allium polyrhizum Furcz. ex Regel. The species studied differed in the structural and functional mechanisms for the adaptation of photosynthetic apparatus to arid conditions. E. sinica has thick, vertical assimilating shoots, which are characterized by a high density (620 mg/cm³) and a small proportion of photosynthetic tissues (13%). The proportion of meso-phyll in the leaves of A. polyrhizum and S. glareosa was two and three times higher, respectively. The low content of phototrophic tissues in E. sinica shoot was compensated for by a high photosynthetic activity of single chloroplasts (25 mg CO₂/(10⁹ chloroplast h)), which was six times higher, than in two other species. Daily course of photosynthesis and transpiration inE. sinica differed from those of A. polyrhizum and S. glareosa by the absence of the midday depression. E. sinica had the highest efficiency of water use (45 mg CO₂/g H₂O) due to a low transpiration rate (0.25 g/g fr wt h). It is concluded that, in E. sinica, the main strategy for adaptation to arid stress is to develop in the shoot a few photosynthesizing cells of high assimilation activity. Such structural organization of photosynthetic organs in ephedra contributes to its higher efficiency of water use and stability of physiological characteristics under changing environmental conditions. These specific features of the structure of assimilating organs and their functional features contribute to a greater expansion of E. sinica with increasing climate aridization in Mongolia.     

Repetitively rated plasma relativistic microwave oscillator with a controllable frequency in every pulse

A repetitively rated microwave oscillator whose frequency can be varied electronically from pulse to pulse in a predetermined manner is created for the first time. The microwave oscillator has a power on the order of 10⁸ W and is based on the Cherenkov interaction of a high-current relativistic electron beam with a plasma preformed before each pulse. Electronic control over the plasma properties allows one to arbitrarily vary the microwave frequency from pulse to pulse at a pulse repetition rate of up to 50 Hz.     

Structural and Functional Changes in the Leaves of Plants from Steppe Communities as Affected by Aridization of the Eurasian Climate

Morphological and physiological characteristics of leaves from plant species collected in steppe communities in the various climatic zones in Eurasia were compared. The changes in leaf structure correlated with the major climatic factors. The mean thickness of leaves increased with increasing mean temperature of July and decreasing mean precipitation, which corresponded to aridity increase. The increased leaf thickness correlated with an increase in the specific leaf weight. The content of chlorophylls (a + b) in leaves greatly varied with plant habitats, whereas the chlorophyll a/b ratio remained unchanged. The chlorophyll content in leaf tissues had a general tendency to decrease with increasing leaf thickness. The leaf chlorophyll content positively correlated (R ² = 0.77) with the proportion of chlorenchyma in leaf tissues. It is concluded that steppe plants adapt to climate aridization at the structural level by increasing the proportion of protective heterotrophic components of the leaf without changing the functional activity of photosynthetic tissues.     

Age-related changes in mast cells and eosinophils of human dermis

In this study, quantitative analysis of inflammatory effectors—mast cells and eosinophils—in derma of people of different ages is performed. The study shows that mast cell quantity in derma increases with age. Eosinophils are rarely observed in human dermis. There are no age-correlated changes of dermal eosinophils quantity observed. Age-correlated dermal fibroblast quantity is established. PCNA+ (proliferating cells nuclear antigen) fibroblast percentage demonstrating their proliferative pool also reliably decreases with age. Results of correlation analysis show that age-correlated increase in mast cells’ quantity is reliably (p < 0.05) correlated with decrease in total number and percentage of PCNA+ fibroblasts in derma. Consequently, age-correlated increase in dermal mast cell may be proposed to be one of the inflammatory and aging mechanisms. Mast cells, whose number increases with aging, may influence dermal fibroblast number with aging.     

C4 plants in the vegetation of Mongolia: their natural occurrence and geographical distribution in relation to climate

The natural geographical occurrence, carbon assimilation, and structural and biochemical diversity of species with C₄ photosynthesis in the vegetation of Mongolia was studied. The Mongolian flora was screened for C₄ plants by using ¹³C/¹²C isotope fractionation, determining the early products of ¹⁴CO₂ fixation, microscopy of leaf mesophyll cell anatomy, and from reported literature data. Eighty C₄ species were found among eight families: Amaranthaceae, Chenopodiaceae, Euphorbiaceae, Molluginaceae, Poaceae, Polygonaceae, Portulacaceae and Zygophyllaceae. Most of the C4 species were in three families: Chenopodiceae (41 species), Poaceae (25 species) and Polygonaceae, genus Calligonum (6 species). Some new C₄ species in Chenopodiaceae, Poaceae and Polygonaceae were detected. C₄ Chenopodiaceae species make up 45% of the total chenopods and are very important ecologically in saline areas and in cold arid deserts. C₄ grasses make up about 10% of the total Poaceae species and these species naturally concentrate in steppe zones. Naturalized grasses with Kranz anatomy,of genera such as Setaria, Echinochloa, Eragrostis, Panicum and Chloris, were found in almost all the botanical-geographical regions of Mongolia, where they commonly occur in annually disturbed areas and desert oases. We analyzed the relationships between the occurrence of C₄ plants in 16 natural botanical-geographical regions of Mongolia and their major climatic influences. The proportion of C₄ species increases with decreasing geographical latitude and along the north-to-south temperature gradient; however grasses and chenopods differ in their responses to climate. The abundance of Chenopodiaceae species was closely correlated with aridity, but the distribution of the C₄ grasses was more dependent on temperature. Also, we found a unique distribution of different C₄ Chenopodiaceae structural and biochemical subtypes along the aridity gradient. NADP-malic enzyme (NADP-ME) tree-like species with a salsoloid type of Kranz anatomy, such as Haloxylon ammodendron and Iljinia regelii, plus shrubby Salsola and Anabasis species, were the plants most resistant to ecological stress and conditions in highly arid Gobian deserts with less than 100 mm of annual precipitation. Most of the annual C₄ chenopod species were halophytes, succulent, and occurred in saline and arid environments in steppe and desert regions. The relative abundance of C₃ succulent chenopod species also increased along the aridity gradient. Native C₄ grasses were mainly annual and perennial species from the Cynodonteae tribe with NAD-ME and PEP-carboxykinase (PEP-CK) photosynthetic types. They occurred across much of Mongolia, but were most common in steppe zones where they are often dominant in grazing ecosystems. Received: 17 March 1999 / Accepted: 1 November 1999     

Granular biogenic amine-containing cells of the rat endometrium as components of the system of mononuclear phagocytes

To 10 non-inbred white mature rats 24 h before sacrifice 7.0 ml of Indian ink colloid solution has been injected intraperitoneally. Histochemical reactions of Falk-Hillarp (catecholamines, serotonin) have been performed on nonfixed cryostat slices of the uterus, those of Cross, Even, Rost (histamine) against non-specific esterase and acid phosphatase. Before carrying out these reactions, the slices have been examined under luminescent microscope LUMAM-I3 by means of luminescent and usual illumination in order to reveal cells, possessing autoluminiscence and containing phagocyted Indian ink particles. Presence of autoluminescence, phagocyted material, catecholamines and serotonin, histamine, nonspecific esterase, acid phosphotase, prostaglandin E2 in the same granular cells of the rat endometrium have been stated. All cellular properties revealed are specific for macrophages. A conclusion is made that granular biogenic amine-containing cells of endometrium can be considered as belonging to the system of mononuclear phagocytes.     

Localization of histamine in uterine structures

By means of luminescent-histochemical method of Cross, Even, Rost histamine is revealed in all uterine structures. Visual and fluorometric data demonstrate uneven distribution of histamine in the organ's structures. A high content of histamine is specific for macrophages and mast cells, less high--in tegmental epithelium and endometrial glands. A low level of histamine have endometrial stroma, smooth myocytes, cells of the serous membrane and vessels. Basing on the literature data, concerning various sensitivity of the uterine tissues to estrogens and regarding effect of the estrogens upon histamine metabolism in the uterine and regarding interconnection of the histamine receptors in the uterus and the estrogens, a suggestion is made that various contents of histamine in the uterine structures depend on various amount of the histamine receptors in them and on different abilities of the uterine tissues to inactivate histamine. The ability of macrophages to accept free forms of bioamines, as it is described in the literature, evidently can be spread to the uterine macrophages, where a high content of histamine is revealed.     

Connective tissue growth factor (CTGF) in the human dermis through ontogenesis

Connective tissue growth factor (CTGF) was examined in the structures of dermis of humans with different ages, from 20 weeks of pregnancy to 85 years. By immunohistochemistry, the fibroblasts and blood vessels positively stained for CTGF were observed in the dermis of all examined ages. An age-dependent increase in the percent of the fibroblasts and blood vessels positively stained for CTGF in the dermis was observed. A statistically significant negative correlation was found between the age-dependent changes in the total number of fibroblasts, percent of the fibroblasts with positive staining for proliferating cell nuclear antigen, and portion of the fibroblasts with positive staining for CTGF. Another statistically significant negative correlation was found between the age-dependent changes in the number of blood vessels and portion of the blood vessels with a positive staining for CTGF. The results suggest that CTGF has an inhibitory influence on the angiogenesis and fibroblast renewal in the human dermis through ontogenesis.     

Histamine distribution in the uterine structures of ovariectomized rats administered estradiol, histamine antagonists and an inhibitor of prostaglandin synthesis

In the experiments performed on ovariectomized rats, using luminescent-histochemical method for revealing histamine after Cross, Ewen and Rost, it has been demonstrated that estradiol facilitates increasing histamine content in the uterine structures, as well as its redistribution--histamine content increases in the glandular and tegmental epithelia, in stromal cells, smooth myocytes and it decreases in macrophages. These manifestations of estradiol action are absent after cymetidin and indometacin, but not tavegil administration. The first two inhibit the morphological effect of estradiol in the uterus, indometacin making it in a greater degree. It is supposed that estradiol action, concerning provision of the uterine structures with histamine, takes place together with prostaglandins participation and at hormonal activation of H2-receptors. Taking into account the literature data on stimulating influence of estradiol on macrophagal phagocytosis and secretion, a conclusion is made that decreasing content of histamine in macrophages at estrogenization results from histamine release by these cells; macrophages are potential sources of histamine in the uterus.