Seedling recruitment in a semi‐arid Patagonian steppe: Facilitative effects of refuse dumps of leaf‐cutting ants

Question: What is the influence of refuse dumps of leaf‐cutting ants on seedling recruitment under contrasting moisture conditions in a semi‐arid steppe? Location: Northwestern Patagonia, Argentina. Methods: In a greenhouse experiment, we monitored seedling recruitment in soil samples from refuse dumps of nests of the leaf‐cutting ant Acromyrmex lobicornis and non‐nest sites, under contrasting moisture conditions simulating wet and dry growing seasons. Results: The mean number of seedling species and individuals were higher in wet than in dry plots, and higher in refuse dump plots than in non‐nest soil plots. The positive effect of refuse dumps on seedling recruitment was greater under low moisture conditions. Both the accumulation of discarded seeds by leaf‐cutting ants and the passive trapping of blowing‐seeds seems not explain the increased number of seeds in refuse dumps. Conversely, refuse dumps have higher water retention capacity and nutrient content than adjacent non‐nest soils, allowing the recruitment of a greater number of species and individual seedlings. Conclusions: Nests of A. lobicornis may play an important role in plant recruitment in the study area, allowing a greater number of seedlings and species to be present, hence resulting in a more diverse community. Moreover, leaf‐cutting ant nests may function as nurse elements, generating safe sites that enhance the performance of neighbouring seedlings mainly during the driest, stressful periods.     

里约热内卢2016奥林匹克公园总体规划

里约热内卢是一个自然城市,她是城市发展和原生自然成功融合的产物。2016年奥运会和残奥会公园的规划场地位于Tijuca和Pedra     

Current Concepts and Future Directions in Differentiated Thyroid Cancer

This paper provides an overview on the biology, monitoring and management of differentiated thyroid cancer (DTC), with particular attention to issues of relevance to clinical chemistry. The incidence of DTC appears to be increasing and management strategies are evolving as we learn more about its natural history and response to therapy. Clinical chemistry techniques play a central role in these protocols. Technical limitations inherent in current monitoring tools can hamper follow-up, although progress is being made. The molecular basis of DTC is being delineated with the potential to develop new strategies for diagnosis, monitoring and management of this condition.     

Bilateral detection thresholds in dextrals and sinistrals reflect the more sensitive side of the nose, which is not lateralized [published erratum appears in Chem Senses 1998 Dec;23(6):761]

Several fundamental questions remain enigmatic concerning human olfactory sensitivity, including (i) whether detection threshold differences exist between the two sides of the nose (and, if so, whether such differences are influenced by handedness) and (ii) whether bilateral (i.e. binasal) stimulation leads to lower thresholds than unilateral stimulation (and, if so, whether the degree of facilitation is inversely related to general olfactory ability). In this study, and well-validated single staircase procedure was used to establish bilateral and unilateral detection thresholds for the cranial nerve I stimulant phenyl ethyl alcohol in 130 right- and 33 left-handed subjects. No differences in sensitivity between the left and right sides of the nose were observed in either group. Bilateral thresholds were lower, on average, than unilateral thresholds when the latter were categorized in terms of left and right nares. However, the bilateral thresholds did not differ significantly from those of the side of the nose with the lower threshold. Overall smell ability, as measured by the University of Pennsylvania Smell Identification Test, did not interact with any of the test measures. These data imply that (i) the left and right sides of the nose do not systematically differ in detection threshold sensitivity for either dextrals or sinistrals and (ii) if central integration of left:right olfactory threshold sensitivity occurs, its effects do not exceed the function of the better side of the nose.      

云南瓶尔小草属一新种

Ophioglossum yongrenense Ching ex Z. R. He et W. M. Chu, sp. nov.Species nova aspectu inter O. kawamuram Tagawa et O. parvum Nishida et Kurita Japonicae, differt a priore frondibus pro parte laminis sterilibus praeditis (in illa frondibus omnino laminis sterilibus non praeditis), a posteriore frondibus pro parte laminis sterilibus non praeditis (in O. parvo Nishida et Kurita frondibus omino laminis sterilibus praeditis).……     

Cortisol, adrenocorticotropic hormone and apolipoprotein synthesis in rat hepatocytes]

The influence of cortisol (5 mg/kg body wt administered daily for 5 and 10 days) on biosynthesis of apoproteins of lipoproteins of very low density in the liver and on the synthesis of apolipoproteins of very low, low, and high density (VLDL, LDL, and HDL apoproteins, respectively) in the blood serum of adrenalectomized animals, and after replacement cortisol therapy was studied. Cortisol treatment during these periods resulted in the VLDL apoproteins biosynthesis inhibition in the rat liver. The synthesis of apolipoproteins was increased by adrenalectomy; this effect was eliminated after replacement cortisol treatment. The apoprotein synthesis was stimulated within 5 hours by single injection of cortisol or ACTH. Study of the blood serum apolipoproteins specific radioactivity indicated metabolic change of lipoproteins, such as disturbed conversion from VLDL to LDL. Single and prolonged cortisol administration led to the opposite results. The authors believe that the metabolic disturbances of lipoproteins in the blood play a more important role in the pathogenesis of cortisol-induced hyperlipidemia than lipoprotein syntesis stimulation in the liver.     

Growth-inhibition drug test with Trypanosoma cruzi culture forms.

A 48-hr drug screening test is described which evaluates inhibition of exponential growth of T. cruzi culture forms by electronic cell count. About 80% of drugs active in vivo produced a greater than 50% growth inhibition, whereas among compounds inactive in vivo, only 19.6% induced such inhibition. Advantages of this test are low cost, rapid results, small amounts of drugs needed, and feasibility without animal facilities. Comparative studies showed that culture forms are not suitable for screening additives to prevent transmission of T. cruzi by banked blood.     

Lectin receptors distribution in the surface membrane of Trypanosoma cruzi blood forms collected from mice submitted to specific treatment.

The authors investigated the distribution of lectin receptors on Trypanosoma cruzi blood forms collected from mice inoculated with, respectively, the drug-resistant and drug-sensitive strains VL-10 and CL, and treated with the two standard active nitroheterocyclic compounds nifurtimox and benznidazole used for treatment of human Chagas' disease. Blood trypomastigotes purified in Fycoll-Hypaque were incubated with fluorescein-labelled lectins Con A, WGA, EE, WFA, TPA and PNA and then microscopically examined. Neither qualitative or quantitative differences in the fluorescence intensity could be detected between the parasites from VL-10 and CL strains submitted or not to treatment. The results suggest that both strains do not differ in their surface membrane carbohydrate moieties. Moreover, the rapid clearance of blood forms from the drug-sensitive strain in animals treated with single doses of both compounds is not likely to depend on membrane alterations expressed by changes in the carbohydrate components. Furthermore, resistance or sensitivity to drugs is not apparently related to carbohydrate distribution on T. cruzi blood forms.