Cultivar-related differences in the distribution of cell-wall-bound thionins in compatible and incompatible interactions between barley and powdery mildew

Leaf-specific thionins of barley (Hordeum vulgare L.) have been identified as a novel class of cell-wall proteins toxic to plant-pathogenic fungi and possibly involved in the defence mechanism of plants. The distribution of these polypeptides has been studied in the host-pathogen system of barley and Erisyphe graminis DC.f.sp. hordei Marchal (powdery mildew). Immunogold-labelling of thionins in several barley cultivars indicates that resistance or susceptibility may be attributed to the presence or absence of thionins at the penetration site in walls and papillae of epidermal leaf cells.All of the leaf-specific thionin genes are confined to the distal end of the short arm of chromosome 6 of barley. None of the genes for cultivarspecific resistance to powdery mildew which have previously been mapped on barley chromosomes are found close to this locus.     

Isolation and partial characterization of human erythrocyte membrane NADH: (Acceptor) oxidoreductase

Gengliosides generally provide a small portion of the complex carbohydrate content of cell surfaces. An exception is the central nervous system where they comprise up to 5–10% of the total lipid of some membranes. This tissue is unique in that the quantity of lipid-bound sialic acid exceeds that of the protein-bound fraction. Over 30 different molecular species have been characterized to date. These range in complexity from sialosylgalactosyl ceramide with 2 sugars to the pentasialoganglioside of fish brain with 9 carbohydrate units. Virtually all cellular and subcellular fractions of brain that have been carefully examined contain gangliosides to one degree or another, but the majority of brain ganglioside is located in the neurons. Their mode of distribution within the neuron has not been entirely clarified by subcellular studies. Calculations based on reported values for axon terminal density and synaptosomal ganglioside concentration in the rat reveal that nerve endings contribute less than 12% of total cerebral cortical ganglioside. It is concluded that the plasma membranes of neuronal processes contain most of the neuronal ganglioside. These and other considerations suggest the possibility that gangliosides may be distributed over the entire neuronal surface.     

A Comparative Study on the Power of van Lieshout and Baddeley's J-Function

Summary functions such as the empty space function F and the nearest neighbour distance distribution function G are often used as test statistics for point patterns. Van Lieshout and Baddeley recently proposed an alternative statistic, the J-function, which is defined as J = (1 — G)/(1 — F). Theoretical advantages of the J-function over the F- and G-statistics are that it measures the type, strength and range of interaction, and that it can be evaluated explicitly for a larger class of models. In this simulation study we investigate empirically how the power of tests based on J compares to that of tests based on F and G.     

Prediction of global geographic distribution of Metcalfa pruinosa using CLIMEX

Globalization has changed the habitats of various species, resulting in harmful pest invasion. Among these pests, Metcalfa pruinosa has caused worldwide economic and hygienic damage in both urban and agricultural/forested areas. It has been reported that prediction of pest distribution is key to the management of pest prevention. Hence, this study aimed to predict the potential geographic distribution of M. pruinosa under the current climate and under a climate change scenario. CLIMEX, modeling software that analyzes the habitat suitability of a target species based on comprehensive climatic and physiological data, was used mainly to establish a map of predictive distribution of M. pruinosa at present and in the future. Based on our simulations, we predict that M. pruinosa will tend to extend its distribution northward in North America and Europe. We conclude that climate change could result in M. pruinosa invasion in a northward direction, suggesting the need for a thorough system of control and prevention.     

Evaluation of ion gradient-dependent H+ transport systems in isolated enterocytes from the chick

Summary The experiments reported here evaluate the capability of isolated intestinal epithelial cells to accomplish net H⁺ transport in response to imposed ion gradients. In most cases, the membrane potential was kept constant by means of a K⁺ plus valinomycin voltage clamp in order to prevent electrical coupling of ion fluxes. Net H⁺ flux across the cellular membrane was examined at pH 6.0 (the physiological lumenal pH) and at pH 7.4 using methylamine distribution or recordings of changes in media pH. Results from both techniques suggest that the cells have an Na⁺/H⁺ exchange system in the plasma membrane that is capable of rapid and sustained changes in intracellular pH in response to an imposed Na⁺ gradient. The kinetics of the Na⁺/H⁺ exchange reaction at pH 6.0 [K _t for Na⁺=57mm,V _max=42 mmol H⁺/liter 3OMG (3-O-methylglucose) space/min] are dramatically different from those at pH 7.4 (K _t for Na⁺=15mm,V _max=1.7 mmol H⁺/liter 3OMG space/min). Experiments involving imposed K⁺ gradients suggest that these cells have negligible K⁺/H⁺ exchange capability. They exhibit limited but measurable H⁺ conductance. Anion exchange for base equivalents was not detected in experiments performed in media nominally free of bicarbonate.     

New records of orange roughy Hoplostethus atlanticus juveniles in Chile

Orange roughy Hoplostethus atlanticus juveniles <24 cm fork length (L_F) (10–17 years old) were recorded for the first time in Chile, when 10 specimens were collected on the continental slope and seamount JF2 in Juan Fernandez Archipelago. The L_F, total mass, anatomical and parasitological information are reported. Relevance to current life‐cycle hypotheses is discussed.     

沙棘对中国亚湿润干旱区的杨树人工林养分分布及生物循环影响

通过将沙棘（ＨｉｐｐｏｐｈａｅｒｈａｍｎｏｉｄｅｓＬ．）与三种杨树品种（小黑杨（Ｐｏｐｕｌｕｓ‘Ｘｉａｏｈｅｉ’）昭林６号杨（Ｐ．‘Ｚａｏｌｉｎ０６’）和欧美杨６４号（Ｐ．ｅｕｒａｍｅｒｉｃａｎｅｃｖ．‘Ｎ３０１６’）的人工林分别按株混和行混两种方式进行混交实验,研究了固氮植物沙棘对亚湿润干旱区的杨树人工林养分分布和循环的影响,连续３ａ的观测研究得以下结果,沙棘叶片的氮,磷和钾的元素粪土了高于杨树     

Spatial and temporal patterns of abundance of coral reef gobies (Teleostei: Gobiidae)

This study investigated the spatial and temporal patterns of abundance of four substratum-associated species of Gobiidae on a heterogeneous reef flat comprised of four distinct habitat zones, and examined microhabitat use within each zone. Asterropteryx semipunctatus had the widest distribution and was the most abundant species in each habitat zone, followed by Amblygobius bynoensis , Valenciennea muralis and Amblygobius phalaena . Significant temporal and spatial differences in mean density were evident. The highest density of A. semipunctatus (312 individuals 10 m^–2) was recorded in a habitat zone dominated by algal-covered rubble, whereas A. bynoensis and V. muralis were most abundant (mean summer density 5·5–5·8 individuals 10 m^–2) in habitats containing both sand and hard substrata. In contrast, A. phalaena was uncommon (mean density ≤ 0·4 individuals 10 m^–2) in all four habitat zones. Significant seasonal differences in abundance were due to the large influx of recruits in summer. Ontogenetic shifts in habitat use were not evident at either the macrohabitat ( i.e. among habitat zones) or microhabitat scale ( i.e. substratum use within zones). At the microhabitat scale, V. muralis consistently exhibited a strong positive association with sand and was rarely associated with hard substrata. In contrast, the two Amblygobius species were commonly associated with both sand and hard substrata, but patterns of microhabitat use differed among habitat zones. Substratum composition at the microhabitat scale may influence spatial patterns of abundance at larger spatial scales by providing essential resources and, or influencing carrying capacity and predation risk.