Eucalyptus is the tree of choice for wood production by farmers in Ethiopia. Although there are many claims about its harmful effect on ecology and water availability, little actual research exists. The main objective of this study was, therefore, to study the extent of harm of Eucalyptus on the ecosystem. This study was conducted at the Koga Watershed near Lake Tana in Ethiopia. Twenty-five farmers were interviewed and a field experiment with three replications was carried out to quantify the effect of Eucalyptus on various soil physical and chemical properties and maize crop measurements and to compare bulk density, soil moisture contents, maize crop counts and shading effects in fields bordered by Eucalyptus and Croton macrostachyus. Our results show that Eucalyptus decreased both soil nutrients and maize yields within 20 m of the trees. Although moisture content was not affected during the monsoon, it decreased faster within 30 m of the Eucalyptus trees than elsewhere. Soils become water repellent, too. Local farmers’ perception agreed with our experimental findings and indicated that Eucalyptus trees are exhausting the once productive land. They also reported that Eucalyptus dries up springs. Despite this, the growers insist on planting Eucalyptus because of its cash income.
A new trypanorhynch cestode, Grillotia borealis sp. n., is described from the spiral intestines of softnose skates of the genus Bathyraja collected from subarctic waters of the North Pacific Ocean: B. parmifera (Bean) (type host), B. aleutica (Gilbert) and B. interrupta (Gill et Townsend) from the Bering Sea and B. minispinosa Ishiyama et Ishihara and B. smirnovi (Soldatov et Pavlenko) from the Sea of Okhotsk off Japan. The new species is distinguished from other species of Grillotia by possession of the following combination of characters: four hooks per principal row, hooks 4(4') distinctly separated from hooks 3(3') of principal row, principal rows separated by 13-15 intercalary hooks in 2-3 rows, hooks 2(2') and 3(3') change in form along their respective files, hooks 1(1') do not change in form along the file, a broad band of microhooks on the external tentacular face, intermediary hooks are lacking, absence of a special basal armature, origin of the retractor muscle near middle of the bulb, average scolex ratio of 1 : 3 : 2 : 0.1, and a hermaphroditic sac. Grillotia borealis consistently favoured the most anterior regions of the spiral intestine. Seventy-one per cent of 21 attached worms occupied the most anterior chamber of the spiral valve and 52 per cent were embedded in the anterior surface of the spiral valve whorls. Factors which may limit the distribution of G. borealis within the spiral intestine of its host are discussed. Statistically significant differences occur in the mucosal morphology of B. aleutica and B. parmifera for villus length, diameter, spatial arrangement and number per unit area along the antero-posterior axis of the spiral intestine.
Bladelets are a common Upper Palaeolithic technological category, often described as a proxy for the Early Upper Palaeolithic. However, bladelet production has already been documented within preceding Initial Upper Palaeolithic techno-complexes, e.g. at Boker Tachtit (Negev Desert, Israel) and Kara-Bom (Altai Republic, Russian Federation). Only isolated bladelets have been reported from the Central European Bohunician. However, a recently discovered and excavated site, Ořechov IV – Kabáty has yielded a large series (over 1,000 items) of micro-blades and bladelets, documenting a higher degree of technological heterogeneity of the Bohunician techno-complex than previously thought. and Čepelky (bladelets) jsou obecně chápány jako charakteristický projev mladopaleolitické technologie. Často jsou dokonce považovány za typické artefakty počáteční fáze mladého paleolitu (EUP). Nicméně se ojediněle na některých lokalitách objevují už v paleolitu středním. Produkce čepelek byla doložena taktéž v iniciálním mladém paleolitu (IUP), jak dokládají například soubory z lokalit Boker Tachtit (Negevská poušť, Izrael) a Kara- -Bom (Altajská Republika, Ruská Federace). Ve středoevropském bohunicienu (součást IUP technokomplexu) byly dosud popsány pouze izolované nálezy čepelek, ale nedávno objevená a zkoumaná lokalita – Ořechov IV – Kabáty v údolí Bobravy nedaleko Brna – poskytla značný počet (přes 1000 kusů) charakteristických mikročepelek, čepelek a velmi drobných levalloiských hrůtků (spadajících metricky do kategorie čepelek). U tohoto souboru je zcela zřejmý trend v mikrolitizaci, který můžeme chápat jako další vývojové stadium, ale může souviset i se vzdáleností od zdroje suroviny či odlišnou funkcí lokality. Dosud ne zcela vyřešená je otázka datování souboru z Ořechova, který se na základě aktuálně dostupných dat jeví jako mladší v porovnání s klasickými lokalitami Bohunice a Stránská skála. Nové poznatky o bohunicienu v zázemí brněnské kotliny dokládají mnohem vyšší stupeň technologicko-typologické heterogenity bohunického technokomplexu ve střední Evropě, než se dosud myslelo. Nicméně nové poznatky dobře zapadají do pestré mozaiky IUP industrií v Euroasii.
The influence of increased solar UV-B radiation on the photosynthetic characteristics in cowpea seedlings (Vigna unguiculata) grown at optimal (Mgs) and low (Mgd) Mg levels were studied. Both higher UV-B and Mgd treatments caused significant drops of photochemical activities and net CO2 uptake rates (PN). Yet the UV-B-induced decrease in the photosynthetic efficiency was lesser in Mgd seedlings. The leaf Chl a fluorescence measurements proved that after receiving an enhanced UV-B radiation these seedlings showed a significant enhancement in their variable parts. The PSM oscillation of slow fluorescence kinetics was remarkably altered by both treatments. The PN also followed a typical inhibitory pattern as seen in photochemical activities. Concentrations of several chloroplast proteins in trifoliate leaves were significantly reduced by Mgd treatment and unaffected by the other two treatments. Whereas the contents of 43-47 kDa polypeptides in primary leaves were markedly reduced with a maximal effect in Mgd seedlings, no major difference was noted for combined stress. and A. Premkumar, G. Kulandaivelu.
The changes in pigment-protein composition of chloroplasts in Vigna unguiculata (L.) Walp seedlings grown under control and ultraviolet-B (UV-B) enhanced radiation at various temperatures were studied. The chlorophyll-protein (CP) complexes isolated from seedlings after 60 h of continuous UV-B enhanced radiation treatment showed temperature-dependent changes in their levels. At 10 ^C, well marked CPI, CP2a, CP47, CP2 and free pigment bands were seen in UV-B treated seedlings while control seedlings had no detectable green bands. UV-B enhanced radiation decreased the level of CPI, CP2a and CP2 complexes which was more pronounced at 20 and 30 °C than at 40 oC. The analysis of chloroplast polypeptides revealed a drastic decrease in the levels of 55, 47, 33, 25, 23, 22 and 17 kDa polypeptides in UV-B treated seedlings at 20 and 30 oC, and marginal decrease in the levels of 47, 43 and 16 kDa polypeptides at 40 ^C. In contrast to this, at 10 oC large increase in many polypeptides was noticed in UV-B treated seedlings.