Transfer of Immunity to Tumour Isografts by the Systemic Administration of Xenogeneic “Immune” RNA

SPECIFIC immunoreactivity can be conferred on lymphoid cells by incubation with RNA-rich extracts prepared from lymphoid tissues exposed to specific antigens in vivo¹ and in vitro^2,3. We have shown transfer of immunity to tumour specific antigens in vivo⁴ and in vitro⁵ by incubation of syngeneic spleen cells in vitro with RNA extracted from the lymphoid tissues of xenogeneic or syngeneic animals immunized with the tumour to be treated. Administration of these spleen cells to normal animals decreased the development and growth of isografts of the same tumour.     

Thermal Inactivation of Plant Growth: Effects on Cotyledon Metabolism

Temperature exposures which normally decrease growth of Pisum sativum seedlings by 50 % were found to be lethal in plants whose cotyledons were removed. Utilization of the two major reserves, starch and protein, decreased at high temperatures. However, the two enzymes responsible for their hydrolysis were thermostable. It appears that the influence of high temperatures on seedling growth is not due to direct effects of temperature on cotyledon metabolism, but rather indirectly through the axis.     

Biochemical Adaptation to the Environment

SYNOPSIS. Biochemical adaptation to environmental parameterssuch as temperature appears to involve two distinct types ofchanges in the organism's chemistry. On the one hand, the quantitiesof certain molecular species present in the cells may change.Alternatively, the actual types of molecules present may vary.Rainbow trout (Salmo gairdneri) acclimated to warm and coldtemperatures exhibit a striking example of this latter typeof adaptation. For all enzymes we have examined in this species,distinct "warm" and "cold" isozymes are present. The isozymesfound in warmacclimated (18°C) trout function well onlyat temperatures above 10–12°C. The isozymes presentin cold-acclimated (4°C) trout function optimally at 2-5°C,temperatures this species normally encounters in winter. Thesedata, plus information on comparable changes in membrane lipids,lead us to propose that adult poikilotherms may undergo a considerabledegree of "biochemical restructuring" on a seasonal basis. Thefactors which control this "restructuring," and the rates atwhich the process occurs at high and low temperatures, are topicsfor future investigation.     

Regulation of Growth in Avena (Oat) Stem Segments by Gibberellic Acid and Abscisic Acid

The purpose of this study was to analyze the nature of the interaction between gibberellic acid (GA₃) and abscisic acid (ABA) in the regulation of growth in excised Avena (oat) stem segments. Growth, compared to sucrose controls, was inhibited by ABA in the range of 10^?4 to 10^?6M. GA₃-promoted growth was also inhibited by ABA in the same concentration range. A Lineweaver-Burk analysis of the interaction between GA₃ and ABA indicated that ABA acts in a non-competitive fashion with GA₃. This same result was obtained previously with GA₃-indoleacetic acid (IAA) and GA₃-kinetin interactions with Avena stem sections. Our results indicate that ABA can inhibit GA₃-promoted growth within physiological concentrations, and that it is probably acting at a different physiological site from that for GA₃.     

Natural distribution, spread, and variation, in the tobacco mosaic virus infecting Nicotiana glauca in Australia

Nicotiana glauca is a naturalised introduced species widely distributed in Australia. A survey of stands in the central zone of its recorded distribution has shown that a type of tobacco mosaic virus which characteristically induces a bright yellow mosaic symptom (TMV-Y) is commonly associated with N. glauca throughout this zone. Surveys of a natural community of N. glauca less than 5 yr old, and in an experimental block, showed that TMV-Y could spread at a rate, and in a pattern, which could not be explained by contact transmission alone, and which indicated that an airborne vector was probably involved in transmission. These results together have led to the conclusion that the common association of TMV-Y with N. glauca is due to spread of the virus by an unknown vector(s). Seed transmission of TMV-Y in N. glauca has not been detected. Molecular hybridisation analysis has shown that all but one of the TMV-Y isolates studied were related to TMV-U², and that the isolate which was unrelated to U², was partially related to TMV-U¹, TMV-U⁵, and tomato mosaic virus. Selected isolates which showed a close relationship to TMV-U², also showed a close relationship to TMV-U⁵, a distant relationship to TMV-U¹, and tomato mosaic, and very little or no relationship with three other tobamoviruses (sunn-hemp mosaic virus, odontoglossum ringspot virus, and cucumber virus 4). These results show that the Australian TMV-Y isolates are similar to the TMV isolated from N. glauca in California.     

A Comparison of Petiolar Growth of Isolated Hazel Cotyledons in Response to Stratification and Exogenous GA3

Following stratification seeds of Corylus avellana exhibitedtheir characteristic ability to germinate at 20 °C undermoist conditions. Stratification of the intact fruit also stimulatedelongation of the cotyledonary petiole when isolated cotyledonswere transferred to moist conditions at 20 °C. GA₃ inducedboth of these effects in non-stratified material. ABA substantiallydecreased seed germination and the response of cotyledonarypetioles to stratification and GA₃. CCC² applied to stratifiedor GA₃-pretreated cotyledons did not depress the final percentageof growing petioles. Cotyledons can clearly regulate the development of their petiolesin the absence of the embryonic axis. It is concluded that thereis at least one gibberellin-sensitive site in the cotyledonscapable of initiating petiole development independent of axiscontrol.     

Aspects of Scotia Sea zooplankton

Information on small scale distributions of three species of Antarctic zooplankton is reviewed. Aggregations of the euphausiid Euphausia superba , the tunicate Salpa thompsoni , and the amphipod Parathemisto gaudichaudii are compared, and the manner in which such aggregations mav arise is discussed. A possible relationship between swarming and feeding activity in E. superba is suggested in which krill are thought to be dispersed whilst feeding but that on repletion they swarm. It is thought that this may account for this species' irregular spatial distribution as recorded bv previous expeditions. A further consequence of this theory is that during the Winter swarming will be minimal.     

Effects of Cycloheximide on Mitosis in Vicia faba Root-meristem Cells

Three different responses of dividing root-meristem cells tocycloheximide have been observed. Cells in anaphase or telophasecan complete these stages and pass into G1; movement of prophaseand metaphase cells into anaphase is reversibly inhibited; entryof G2 cells into mitosis is irreversibly inhibited. While thislast effect is probably a consequence of inhibition of proteinsynthesis by cycloheximide, it is suggested that the reversiblemitotic arrest induced by the drug results from inhibition ofsome other cellular activity, possible related to energy transfer.     

The relation of Late Ordovician glaciation to the Ordovician-Silurian changeover in North American brachiopod faunas

Sheehan, P. M.: The relation of Late Ordovician glaciation to the Ordovician-Silurian changeover in North American brachiopod faunas.
The Ordovician-Silurian changeover of brachiopod faunas in North American epicontinental seas involved the abrupt extinction of endemic Late Ordovician stocks and subsequent repopulation of North American seas by Old World taxa. The Late Ordovician Gondwanaland glaciation may have lowered sea levels sufficiently to place severe stress on the widespread shallow marine faunas in North America, resulting in their eventual extinction. The Late Ordovician depositional history in North America is not well enough known to establish the presence of a latest Ordovician regression, but the earliest Silurian was an interval of off-lap in North America. Therefore, the glacial lowering of sea level is considered to be the most likely cause of the faunal changeover.