RECOVERY OF NATIVE AND APPLIED AUXIN FROM THE DARK-GROWN ‘ALASKA’ PEA SEEDLING

Scott, Tom K., and Winslow R. Briggs. (Stanford U., Stanford, Calif.) Recovery of native and applied auxin from the dark-grown ‘Alaska’ pea seedling. Amer. Jour. Bot. 50(7): 652–657. Illus. 1963.—The distribution and movement of “free” endogenous and applied auxin were determined in the 7-day-old dark-grown ‘Alaska’ pea epicotyl by means of short-term ether extraction. A general decrease in total endogenous auxin content took place from apex to base within the growing as well as the non-growing regions. Factors other than growth itself may be responsible for this decrease. Auxin distribution changes, as they occur following the removal of the apical bud, may reflect an incompletely polar transport system operating in the epicotyl. This suggestion was supported by following the movement of indole-3-acetic acid applied in lanolin paste. The results presented are related to similar experiments performed on the light-grown ‘Alaska’ pea seedling as well as on other vascular plants.     

RECOVERY OF NATIVE AND APPLIED AUXIN FROM THE LIGHT-GROWN ‘ALASKA’ PEA SEEDLING

Scott , Tom K., and Winslow R. Briggs . (Stanford U., Stanford, Calif.) Recovery of native and applied auxin from the light-grown ‘Alaska’ pea seedling. Amer. Jour. Bot. 49(10): 1056–1063. Illus. 1962.—The physiological status of both endogenous and exogenously applied auxin was compared in the epicotyl of the 9-day-old light-grown ‘Alaska’ pea (Pisum sativum L.) by means of agar-diffusion and short-term ether extraction. A detailed analysis of endogenous auxin revealed a linear basipetal decrease in diffusible auxin within the growing region. A decrease in extractable auxin occurred only within the most mature region. The capacity for uptake of indole-3-acetic acid (IAA), applied in lanolin paste, was compared in different regions of the epicotyl. The fifth and most apical internode had the greatest capacity for uptake as measured by extraction. A reduced capacity was found in more basal internodes. The transport rate of applied IAA, under conditions of optimal uptake, was 10–12 mm/hr. An application of IAA for 24 hr resulted in a dramatic increase in auxin content throughout the length of the epicotyl compared to that found in the normal control. There was no apparent gradation in content from apex to base. An increase of diffusible auxin was also found, but only in the fourth and third internodes. That no such increase was detected in the basal 3 internodes suggested that the auxin transport system within this region had special properties related to a transition between shoot and root vascular patterns.     

DETECTION OF INFECTIOUS VIRUS AND VIRAL RNA IN THE MYOCARDIUM OF MICE INFECTED EXPERIMENTALLY WITH COXSACKIE VIRUS’B

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THE RELEVANT USE OF THE TRADITIONAL TUNISIAN GAME ‘‘RAQASSA’’ FOR CARDIOVASCULAR STIMULATION IN SCHOOLCHILDREN

The aim of this study was to investigate the heart rate (HR) responses, the rate of perceived exertion (RPE), and the feeling during physical education schooling while performing traditional games activities compared to intermittent exercise. Nineteen pre-pubertal children randomly performed on different days two types of lessons (intermittent running mode vs. traditional Tunisian “Raqassa” game) lasting 12-min each. HR was continuously recorded during both lessons, while ratings of perceived exertion and Feeling values were recorded after the sessions. The mean HR value during the traditional game was significantly higher than during intermittent exercise (p<0.05). Conversely, the perceived exertion score was significantly higher after intermittent exercise than the traditional exercise game (p<0.05), showing that the higher cardiovascular strain of the game was perceived as “lighter” than the run. Simultaneously, the children''s Feeling was significantly higher after the traditional game than intermittent exercise (p<0.001), showing a higher satisfaction from playing with respect to running. Exercise based on the “Raqassa” traditional game could be used in pre-pubertal children as an alternative or as an additional method for suitable cardiovascular stimulation during physical education lessons with lower perceived exertion and better feeling compared to intermittent running.     

THE DISTRIBUTION AND ACCUMULATION OF SELENIUM IN ROOTS AND SHOOTS OF PLANTS NATURALLY GROWN IN THE SOILS OF KEBAN’S PB-ZN-F MINING AREA,TURKEY

The objective of this study is to determine the distribution factors and enrichment coefficients between soil and plant parts by studying the accumulation and distribution of selenium (Se) in the roots and shoots of different plants. The plants (9 samples of Euphorbia macroclada, 5 samples of Verbascum cheiranthifolium, 8 samples of Astragalus gummifer) and their associated soil samples were collected from the Keban mining area. The roots and the shoots of these plants, together with the associated soils, were analyzed by ICP-MS. The mean Se value of the contaminated surface soils was found to be two to five times higher than those of previously studied uncontaminated surface soils. Se concentrations of the plant parts were lower than those in their associated alkaline soils, where the plants were grown, except for in the shoots of A. gummifer. Mean Se concentrations in the roots of E. macroclada, V. cheiranthifolium, and A. gummifer were 0.82, 0.22, and 0.47 mg kg^?1 on a dry weight basis, respectively, while Se concentrations were 0.29, 0.26, and 2.66 mg kg^?1 in the shoots on a dry weight basis, respectively. The enrichment coefficients and the distribution factors of those plants were lower than 1, except for the distribution factors of V. cheiranthifolium and A. gummifer plants. Thus, it appeared that the shoots of these plants could make them efficient bioaccumulator plants for Se because of high distribution factors and enrichment coefficients. Due to such factors, they can also be used to clean or rehabilitate soils and areas contaminated with Se.     

A MORPHOLOGICAL AND HISTOLOGICAL STUDY OF THE TOMATO MUTANT ‘CURL’

The dominant tomato mutant ‘Curl’ differs from normal plants in several striking respects including the following: misshapen laminar structures such as leaves, sepals, and petals; stunted petiole and rachis; and persistent growth of blade and stem tissue from the adaxial surface of the rachis. These tissues as well as others which appear morphologically normal show gross histological abnormalities. Also evident in sections of mutant tissue is the appearance of areas containing numerous crystalline inclusions and a lack of bodies showing a stainable starch reaction in palisade and mesophyll of leaves and in endodermis and pith cells of the stem.     

MANAGEMENT,CONSERVATION AND RESEARCH OF INTERNATIONALLY SHARED WATERCOURSES IN SOUTIIERN AFRICA—NAMIBIAN EXPERIENCE WITH THE OKAVANGO RIVER AND RIVERS OF THE EASTERN CAPRIVI

Summary

Although the emphasis of the recent National Rivers Research Initiative (now the Research Programme for the Management of Rivers) in South Africa was on river research in that country, the reality is that in southern Africa many watercourses are shared by more than one country. Therefore a central issue in integrated river basin management and development should be the recognition of the principle of international joint planning, conservation, monitoring and research.

Co-operation and a better understanding of shared waters would prevent deleterious impacts, not only in the country where they occur, but also in those downstream. With this in mind, since the early 1980s Namibia has worked on joint cross-border projects in efforts to manage and conserve her shared water bodies. These include joint river gauging exercises, biological control of Saivinia molesta in the eastern Caprivi region and, more recently, the application of a biological monitoring technique, the South African Scoring System version 4, to north-eastern perennial rivers.

The formation of the Joint Permanent Water Commission between Botswana and Namibia enabled the Departments of Water Affairs of both countries to work together on their shared rivers. The establishment of the Permanent Okavango River Basin Water Commission between Angola, Botswana and Namibia in 1994 improved this co-operation even further. Namibia and its' counterparts are thus committed to sharing information, co-ordinating research and monitoring activities and to undertaking detailed studies to improve their knowledge of these shared systems.

Such cross-border co-operation is vital for the survival of shared river systems not only as ecological entities in their own right, but also as sources of water, power and the other resources they provide, both directly and indirectly, to the human and wildlife populations that they support.     

HOW CLOSELY CORRELATED ARE MOLECULAR AND QUANTITATIVE MEASURES OF GENETIC VARIATION? A META‐ANALYSIS

The ability of populations to undergo adaptive evolution depends on the presence of quantitative genetic variation for ecologically important traits. Although molecular measures are widely used as surrogates for quantitative genetic variation, there is controversy about the strength of the relationship between the two. To resolve this issue, we carried out a meta-analysis based on 71 datasets. The mean correlation between molecular and quantitative measures of genetic variation was weak (r = 0.217). Furthermore, there was no significant relationship between the two measures for life-history traits (r = -0.11) or for the quantitative measure generally considered as the best indicator of adaptive potential, heritability (r = -0.08). Consequently, molecular measures of genetic diversity have only a very limited ability to predict quantitative genetic variability. When information about a population's short-term evolutionary potential or estimates of local adaptation and population divergence are required, quantitative genetic variation should be measured directly.     

ON NEW MATERIAL OF STEGODON WITH RECOLLECTIONS OF THE CLASSIFICATION OF STEGODON IN CHINA

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