Comparison of the distribution of dynorphin systems and enkephalin systems in brain

A study of the anatomical distribution of the endogenous opioid dynorphin in rat brain showed that the peptide is localized in a widespread system with multiple cell groups and projections. This network is revealed by the use of multiple antiserums against dynorphin and can be distinguished from the system containing methionine-enkephalin and leucine-enkephalin, which is mapped by the use of antiserums against the enkephalins and biosynthetically related peptides in the adrenal. It thus appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphin family.     

Effect of pre-medication on gastroduodenoscopy in isoflurane-anesthetized cats

The pre‐medicant chosen may influence the ease with which gastroduodenoscopy (GD) is performed. The purpose of this study was to evaluate the relative ease of GD in cats under ketamine and isoflurane anesthesia after IM injection of hydromorphone (H, 0.1 mg kg^?1), hydromorphone plus glycopyrrolate (HG, 0.1 mg kg^?1 (H), 0.01 mg kg^?1 (G)), medetomidine (M, 0.03 mg kg^?1), or butorphanol (B, 0.4 mg kg^?1). Eight cats were assigned randomly to receive each treatment in a cross‐over design with at least 7 days between treatments. Twenty minutes after pre‐medication, medetomidine produced greater (p = 0.001) sedation than the other treatments when assessed, using a subjective ordinal scale. The cats were injected with ketamine (10 mg kg^?1 IM), orotracheally intubated, connected to a pediatric circle breathing system, and allowed to spontaneously breathe isoflurane in oxygen. Once end‐tidal isoflurane concentration was stable at 1.4% for 15 minutes, endoscopy was started. A single endoscopist (REG), who was unaware of the treatment used, performed all endoscopies. The endoscopist scored the difficulty of endoscopy subjectively (0–3). The significance of differences between treatments was evaluated using Friedman's test. Time for entering the stomach was 9.4 (4.7–15.9) (median (minimum–maximum)), 6.6 (5.2–11.7), 8.4 (6.3–16.5), and 7.7 (5.1–14.7) seconds and for entering the duodenum from the stomach was 20.5 (13.8–40.9), 18.2 (10.3–39.8), 20.2 (16.2–119.5), and 22.2 (11.8–83.8) seconds for H, HG, M, and B treatments, respectively. There were no significant differences in the time for, or difficulty of, endoscopy. We conclude that any of these drugs can be used satisfactorily at the doses and combinations tested to pre‐medicate cats prior to general anesthesia for GD.     

Otarine herpesvirus-1: a novel gammaherpesvirus associated with urogenital carcinoma in California sea lions (Zalophus californianus)

The incidence of neoplasia in California sea lions (CSLs) is considered to be unusually high. Electron microscopic examination of some of these urogenital tumours revealed the presence of virions with typical herpes-like structure. While current attempts to cultivate this virus have not been successful, molecular studies employing DNA extracted from tumour tissues allowed both the classification of the agent and its identification in tumours and archived tissue samples. Two genome fragments generated using degenerate primers in PCR demonstrated highest identities with other mammalian gammaherpesviruses. Phylogenetic analysis showed that this novel virus, tentatively designated Otarine herpesvirus-1 (OtHV-1), grouped with members of the gammaherpesvirus subfamily and was distinct from PHV-2, a previously described pinniped gammaherpesvirus. An OtHV-1 specific PCR was established and used to investigate the presence of this virus in CSL tissues. PCR of DNA isolated from animals with these tumours, demonstrated that this virus was present in 100% (16/16) of tumours. Furthermore, DNA extracted from archived brain and muscle tissues was also positive in 29% (4/14) and 50% (7/14) of cases examined. This preliminary study provides evidence to support the hypothesis that the presence of this novel gammaherpesvirus is a factor in the development of urogenital carcinoma in CSLs.     

Frost resistance in the tropical palm Euterpe edulis and its pattern of distribution in the Atlantic Forest of Argentina

Frost resistance and subzero temperature effects on photosynthesis, survival and distribution were studied in Euterpe edulis, a tree palm species of the Atlantic Forest, near the southern limit of the species distribution. E. edulis grows under the forest canopy and is absent from forest stands located near bottom valleys. This palm species has been commercially exploited for palm hearts, making it the most important non-timber forest species in North-Eastern Argentina. Its distribution was studied in relation to the frequency and intensity of subzero temperatures along a topographic gradient. E. edulis abundance was higher at the highest site and decreased or became absent towards the lowest site. Subzero temperatures during each of three winter seasons were observed in the lowest site. The medium and high elevation sites never experienced absolute minimum temperatures below 0 °C. Forest structure, fraction of solar radiation transmitted through the canopy and soil water potentials did not change substantially along the gradient. After a low temperature period in winter, the maximum quantum yield in E. edulis leaflets was relatively low in individuals at the low elevation site while having normal values at the medium and high elevation sites. Thermal analysis indicated that E. edulis saplings can supercool down to about −10 °C and do not tolerate extracellular ice formation. Ice formation was observed at about −4 °C, relatively close to the equilibrium freezing temperature, only after an increase in ambient humidity resulted in dew formation on the plant surface. Dew formation is commonly observed in valleys during the winter season. This observation gives further support to the hypothesis that strong infrequent frost events could be an important environmental factor determining the spatial distribution pattern of E. edulis in the Atlantic Forest of Argentina.     

Dynamics of transpiration, sap flow and use of stored water in tropical forest canopy trees

In large trees, the daily onset of transpiration causes water to be withdrawn from internal storage compartments, resulting in lags between changes in transpiration and sap flow at the base of the tree. We measured time courses of sap flow, hydraulic resistance, plant water potential and stomatal resistance in co-occurring tropical forest canopy trees with trunk diameters ranging from 0.34-0.98 m, to determine how total daily water use and daily reliance on stored water scaled with size. We also examined the effects of scale and tree hydraulic properties on apparent time constants for changes in transpiration and water flow in response to fluctuating environmental variables. Time constants for water movement were estimated from whole-tree hydraulic resistance (R) and capacitance (C) using an electric circuit analogy, and from rates of change in water movement through intact trees. Total daily water use and reliance on stored water were strongly correlated with trunk diameter, independent of species. Although total daily withdrawal of water from internal storage increased with tree size, its relative contribution to the daily water budget (approximately 10%) remained constant. Net withdrawal of water from storage ceased when upper branch water potential corresponded to the sapwood water potential (Psi(sw)) at which further withdrawal of water from sapwood would have caused Psi(sw) to decline precipitously. Stomatal coordination of vapor and liquid phase resistances played a key role in limiting stored water use to a nearly constant fraction of total daily water use. Time constants for changes in transpiration, estimated as the product of whole- tree R and C, were similar among individuals (~0.53 h), indicating that R and C co-varied with tree size in an inverse manner. Similarly, time constants estimated from rates of change in crown and basal sap flux were nearly identical among individuals and therefore independent of tree size and species.     

Water relations, gas exchange, and nutrient response to a long term constant water deficit

Wheat plants (Triticum aestivum) were grown for 43 days in a micro-porous tube nutrient delivery system. Roots were unable to penetrate the microporous tube, but grew on the surface and maintained capillary contact with the nutrient solution on the inside of the tube through the 5-micron pores of the porous tube. Water potential in the system was controlled at -0.4, -0.8, and -3.0 kPa by adjusting the applied pressure (hydrostatic head) to the nutrient solution flowing through the microporous tubes. A relatively small decrease in applied water potential from -0.4 to -3.0 kPa resulted in a 34% reduction of shoot growth but only a moderate reduction in the midday leaf water potential from -1.3 to -1.7 MPa. Carbon dioxide assimilation decreased and water use efficiency increased with the more negative applied water potentials, while intercellular CO2 concentration remained constant. This was associated with a decrease in stomatal conductance to water vapor from 1.90 to 0.98 mol m-2 s-1 and a decrease in total apparent hydraulic conductance from 47 to 12 micromoles s-1 MPa-1. Although the applied water potentials were in the -0.4 to -3.0 kPa range, the actual water potential perceived by the plant roots appeared to be in the range of -0.26 to -0.38 MPa as estimated by the leaf water potential of bagged plants. The amount of K, Ca, Mg, Zn, Cu, and B accumulated with each unit of transpired water increased as the applied water potential became less negative. The increase in accumulation ranged from 1.4-fold for K to 2.2-fold for B. The physiological responses observed in this study in response to small constant differences in applied water potentials were much greater than expected from either the applied water potential or the observed plant water potential. Even though the micro-porous tube may not represent natural conditions and could possibly introduce morphological and physiological artifacts, it enables a high degree of control of water potential that facilitates the investigation of many aspects of water relations not practical with other experimental systems.     

Sulfur: incorporation into the transfer fraction of soluble ribonucleic acid

When S(35)-labeled soluble RNA from Escherichia coli K 38 is subjected to gel filtration, four fractions of RNA are obtained by elution. Only one RNA fraction, the transfer RNA, contains sulfur, presumably as thionucleotides. Treatment with ribonuclease suggests that the incorporated sulfur is an integral part of the polynucleotide chain; digestion with alkali yields a mixture of products containing sulfur, the major one being eluted in a position similar to uridine diphosphate upon Dowex-l chromatography. Analysis by countercurrent distribution of S(35)-labeledtransfer RNA from E. coli B reveals that the incorporated sulfur is found in many RNA's that accept amino acids, but the possibility remains that not all acceptor RNA's contain sulfur.