Biochemical and immunochemical analysis of the arrangement of connexin43 in rat heart gap junction membranes

A 43 × 10^3 M_r protein (designated connexin43 or Cx43) is a major constituent of heart gap junctions. The understanding of its arrangement in junctional membranes has been extended by means of site-directed antibodies raised against synthetic peptides of Cx43. These represent part of the first extracellular loop (EL-46), the cytoplasmic loop (CL-100), the second extracellular loop (EL-186) and carboxy-terminal sequences (CT-237 and CT-360). All of the antibodies raised reacted with their respective peptides and the Cx43 protein on Western blots. By immunoelectron microscopy two of the antibodies (CL-100 and CT-360) were shown to label the cytoplasmic surface of isolated gap junction membranes. Immunofluorescent labeling at locations of neonatal cardiac myocyte-myocyte apposition required an alkali/urea treatment when the EL-46 and EL-186 antibodies were used. Immunoblot analysis of endoproteinase Lys-C-digested gap junctions revealed that the Cx43 protein passed through the lipid bilayer four times. Alkaline phosphatase digestion of isolated junctions was used to show that the CT-360 antibody recognized many phosphorylated forms of Cx43. Our results unequivocally confirm models of the organization of Cx43 that were based on a more limited set of data and a priori considerations of the sequence

Agronomic and environmental impacts of a single application of heat-dried sludge on an Alfisol

A field experiment was conducted on Alfisols in South-West France to assess the agronomic and environmental impacts of a single application of heat-dried sludge pellets at 11.1 Mg dry matter ha-1. The sludge pellets, with a moisture level of 9.5%, were spread on an irrigated crop of maize (Zea mays L.). This treatment was compared with inorganic fertilization (urea and diammonium phosphate mixed with KCl). Soil properties, yield and the composition of maize and the quality of drained water were monitored over 1 year to detect any changes resulting from sludge application. Amongst several determined soil properties, only two were significantly modified by the sludge application: The nitric nitrogen stock of the soil was higher in the inorganic fertilized plot, whereas Olsen-P soil content was higher in the sludge-amended plot. Agronomic recovery rates of N and P added by sludge were high: For the first crop following application, total amounts of N and P supplied by the sludge had the same efficiency as approximately 45% of the N and P amounts supplied by inorganic fertilizer. This ratio was 7% for the N uptake by the second maize crop. The quality and quantity of maize were equally good with both types of fertilization. During the 2 years following sludge spreading, N leaching remained as low in the sludged plot as in the inorganically fertilized one. The Cu, Zn, Cr, Cd, Pb and Ni composition of the drainage water was affected by neither of the types of amendment. From the heavy-metal contents of the soil, water and maize monitored over 1 year in the field experiment and from literature data for cow manure and atmospheric emissions, a theoretical balance between crop soil heavy-metal input and output over one century was drawn up. The long-term impact of cow manure on Zn, Ni and Cr in soil is higher than that of the studied heat-dried sludge. Obviously, sludge tended to cause a strong increase in soil Cu storage, valued for these soils, which are otherwise very Cu deficient

Short photoperiod-induced decrease of histamine H3 receptors facilitates activation of hypothalamic neurons in the Siberian Hamster

Nonhibernating seasonal mammals have adapted to temporal changes in food availability through behavioral and physiological mechanisms to store food and energy during times of predictable plenty and conserve energy during predicted shortage. Little is known, however, of the hypothalamic neuronal events that lead to a change in behavior or physiology. Here we show for the first time that a shift from long summer-like to short inter-like photoperiod, which induces physiological adaptation to winter in the Siberian hamster, including a body weight decrease of up to 30%, increases neuronal activity in the dorsomedial region of the arcuate nucleus (dmpARC) assessed by electro physiological patch-clamping recording. Increased neuronal activity in short days is dependent on a photoperiod-driven down-regulation of H3 receptor expression and can be mimicked in long-day dmpARC neurons by the application of the H3 receptor antagonist, clobenproprit. Short-day activation of dmpARC neurons results in increased c-Fos expression. Tract tracing with the trans-synaptic retrograde tracer, pseudorabies virus, delivered into adipose tissue reveals a multisynaptic neuronal sympathetic outflow from dmpARC to white adipose tissue. These data strongly suggest that increased activity of dmpARC neurons, as a consequence of down-regulation of the histamine H3 receptor, contributes to the physiological adaptation of body weight regulation in seasonal photoperiod

Periglacial Features From Morfee Mountain, North-Central British Columbia

Six periglacial features (sorted polygons, sorted steps, sorted nets, sorted stripes, sorted circles, felsenmeer and a possible altiplanation terrace) are described from a new location in Central British Columbia (locally known as Morfee Mountain, 55 deg. 26 sec. N, 123 deg. 02 sec. W) between 1300-1650 m elevation. These features are local in distribution over an area of several square km. Observations on specific features indicate a continuum of intermediate forms between sorted nets, sorted polygons and sorted stripes. The elevation of these features supports the suggestion of Brown and Pewe (1973) that the lower elevation of permafrost and periglacial features should rise progressively southward along a north-south transect through the Western Cordillera

A Rare Form of Silene acaulis L. (moss Campion) from British Columbia

While conducting an Ecological Reserves survey of Morfee Mountain in North Central British Columbia (55° 26' N, 123° 04' W) during mid-July 1971, the author noted an interesting variation of flower colour in Silene acaulis L. subsp. subacaulescens (F.N. Williams) Hult. The flower colours of Silene acaulis are usually purple, pink or lavender throughout its range. The majority of the individuals of this species on Morfee Mountain conformed to the usual flower colour. However, one individual plant with pure white petals was observed .... The specimen was collected near the British Columbia Telephone Company microwave relay station on Morfee Mountain at an elevation of about 1700 m. ... Although the white-flowered form of Silene acaulis is not unknown, Hultén (1968) notes that this form is rare, thus making the find an interesting observation for both the amateur botanist and the more serious student of intraspecific variation in plants

Domestic and Commercial Vegetable Gardening in Dawson City, Yukon Territory, 1980

Canadian subarctic agriculture has not been a widespread practice. Because of increasing northern populations associated with industrial development, and the high cost of fresh produce, the practicality and success of subarctic gardening are examined. Dawson City was chosen for study because of its long history of gardening. In 1980 there were 50 domestic gardens, 56 greenhouses, and three commercial gardens which supplied produce both locally and to Whitehorse and Inuvik. The study documents the following crops: cabbage, cauliflower, broccoli, Brussels sprouts, carrots, turnips, kohlrabi, radish, beans, peas, potatoes, lettuce, kale, beetroot, Swiss chard, celery, onions, cucumber, tomatoes, zucchini, corn, peppers, leeks, squash, sunflowers and a large variety of herbs. The specific crop varieties used by gardeners are noted along with observations on their relative success, planting and harvesting dates and special gardening practices.Key words: agriculture, gardening, vegetable cultivationMots clés: agriculture, jardinage, culture de légume