The role of aquaporins and membrane damage in chilling and hydrogen peroxide induced changes in the hydraulic conductance of maize roots

When chilling-sensitive plants are chilled, root hydraulic conductance (L(o)) declines precipitously; L(o) also declines in chilling-tolerant plants, but it subsequently recovers, whereas in chilling-sensitive plants it does not. As a result, the chilling-sensitive plants dry out and may die. Using a chilling-sensitive and a chilling-tolerant maize genotype we investigated the effect of chilling on L(o), and its relationship to osmotic water permeability of isolated root cortex protoplasts, aquaporin gene expression, aquaporin abundance, and aquaporin phosphorylation, hydrogen peroxide (H(2)O(2)) accumulation in the roots and electrolyte leakage from the roots. Because chilling can cause H(2)O(2) accumulation we also determined the effects of a short H(2)O(2) treatment of the roots and examined the same parameters. We conclude from these studies that the recovery of L(o) during chilling in the chilling-tolerant genotype is made possible by avoiding or repairing membrane damage and by a greater abundance and/or activity of aquaporins. The same changes in aquaporins take place in the chilling-sensitive genotype, but we postulate that membrane damage prevents the L(o) recovery. It appears that the aquaporin response is necessary but not sufficient to respond to chilling injury. The plant must also be able to avoid the oxidative damage that accompanies chilling.     

Evaluation of a Community’s Risk for Canine Parvovirus and Distemper Using Antibody Testing and GIS Mapping of Animal Shelter Intakes

This cross-sectional study aimed to identify where dogs with negative antibody tests to canine parvovirus (CPV) and canine distemper virus (CDV) originated when entering a community shelter, using a commercially available ELISA antibody test and Geographic Information Systems mapping. Of 2745 canines entering during a three-month period, 1056 test results were obtained. Dogs or puppies weighing over 2 lb were eligible if they could be humanely, nonchemically restrained for phlebotomy. Age and minor health issues weren't exclusions. Dogs were excluded if trained personnel were concerned health would be compromised by phlebotomy. Blood samples were collected within 24 hours of entry. Four hundred and twenty-seven (40%) dogs had positive antibody test results for both viruses, 422 (40%) were positive for CPV, 37 (4%) were positive for CDV, and 170 (16%) were negative for both. Mapping revealed geographic patterns for dogs with negative antibody tests. This shelter admitted dogs with negative CPV and/or CDV antibody tests from defined community areas. Targeting vaccination efforts in communities to areas where dogs with negative antibody tests originate could be an effective wellness strategy.     

Aggressive Thresholds of Male Pacific Treefrogs for Advertisement Calls Vary with Amplitude of Neighbors' Calls

In breeding choruses, male Pacific treefrogs (H. regilla) produce advertisement and encounter calls. The role of each call type in establishing intermale spacing patterns was investigated by playing back, at various amplitudes, recordings of these vocalizations to resident males. The aggressive threshold of a male for each call type was defined as the lowest amplitude of playback that elicited encounter calls. Pacific treefrogs consistently had lower aggressive thresholds to playbacks of encounter calls than to playbacks of advertisement calls. Aggressive thresholds to playbacks of advertisement calls were positively correlated with the maximum amplitude of the advertisement calls of neighboring males, as measured at the position of the focal male.     

Female marsh wrens do not provide evidence of anatomical specializations of song nuclei for perception of male song

In songbirds the forebrain nuclei HVC (high vocal center) and RA (robust nucleus of the archistriatum) are larger in individuals or species that produce larger song repertoires, but the extent to which the size of these nuclei reflects a need for either producing or perceiving large repertoires is unknown. We, therefore, tested the hypothesis that species differences in the size of song nuclei reflect a commitment of “brain space” to the perceptual processing of conspecific song. The two species of marsh wren (Cistothorus palustris western and eastern) provide a good test case. Western males produce larger song repertoires, and have larger HVC and RA than do eastern males. Female marsh wrens do not sing, and if they use their song nuclei to assess conspecific male song repertoires, then we predicted that measurable cellular and nuclear parameters of HVC and RA would be greater in western than eastern female wrens. For males we confirmed that the volumes of HVC and RA, and cellular parameters of HVC, are greater in western than in eastern birds. These nuclei were also considerably larger in males than in conspecific females. Western and eastern female wrens, however, did not differ in any measured parameters of HVC or RA. Females of these wren species thus do not provide any direct evidence of anatomical specializations of song nuclei for the perceptual processing of conspecific male song. 1994 John Wiley & Sons, Inc.     

Closed-Chest Massage: An Effective Resuscitative Procedure for the Maintenance of the Circulation During Cardiac Arrest

Reports of clinical benefits of closed-chest cardiac resuscitation refute recently published studies contesting its effectiveness.Our experimental investigations demonstrate that closed-chest massage is able to achieve adequate cerebral circulation and oxygenation during cardiac arrest.Clinical studies indicate that a significant number of coronary patients can be saved if a monitor system is used to warn of the onset of ventricular fibrillation or arrest. To be successful, closed-chest resuscitation must be instituted within the four-minute limit after onset of cardiac arrest. When ventricular fibrillation occurs, electrical countershock is usually obligatory. Cardiac pacemaking is a specific necessity for patients with ventricular arrest.     

Immunogold-localization and synthesis of an oil-body membrane protein in developing soybean seeds

The synthesis of a major oil-body membrane brotein was studied in maturing soybean (Glycine max (L.) Merr.) cotyledons. The membrane contained four abundant proteins with apparent molecular mass (M_r) of 34000, 24000, 18000 and 17000. The M_r=24000 protein (mP 24) was selected for more detailed analysis. The protein was purified to apparent homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isolated from the gel by electroelution or chemical hydrolysis of gel crosslinks. It was then used to elicit rabbit antibodies which were judged to be specific when assayed by SDS-PAGE-immunoblot procedures. The mP 24 was localized in immature soybean cotyledon cells by indirect immunogold procedures on thin sections of Lowicryl- and LR-White-embedded tissue. Indirect labeling with the primary antiserum followed by colloidal gold-protein A showed specific labeling of the oil-body membrane and an absence of label on the other subcellular organelles including the endoplasmic reticulum (ER). Parallel tissue samples were studied by conventional transmission electron microscopy. Although segments of the ER were observed to be closely juxtaposed to the oil bodies, continuity between the two organelles was not observed. The synthesis of mP 24 was studied by in-vitro translation and in-vivo labeling with [³H]leucine followed by indirect immunoaffinity isolation of the labeled products. The SDS-PAGE fluorography results indicated that the primary translation product and the in-vivo synthesized protein have the same M_r, and this is also the same M_r as the protein in the mature membrane.Abbreviations and symbols DATD N N'-diallyltartardiamide - EM electron microscopy/scopic - ER endoplasmic reticulum - IgG immunoglobulin G - M_r apparent molecular mass - PBS phosphate-buffered saline - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis - TBS Trisbuffered saline     

Interaction of [3H](–)-SKF-10,047 with Brain σ Receptors: Characterization and Autoradiographic Visualization

The sigma opiates differ from other opiates in their stimulatory and psychotomimetic actions. The sigma opiate [3H](-)-SKF-10,047 has been used to characterize sigma receptors in rat nervous tissue. Binding of [3H](-)-SKF-10,047 to rat brain membranes was of high affinity, saturable, and reversible. Scatchard analysis revealed the apparent interaction of this drug with two distinct binding sites characterized by affinities of 0.03 and 75 nM (5 mM Tris-HCl buffer, pH 7.4, at 4 degrees C). Competition analyses involving rank order determinations for a series of opiates and other drugs indicate that the high-affinity binding site is the mu opiate receptor. The lower-affinity site (revealed after suppression of mu and delta receptor binding) has been identified as the sigma opiate/phencyclidine receptor. In vitro autoradiography has been used to visualize neuroanatomical patterns of receptors labeled using [3H](-)-SKF-10,047 in the presence of normorphine and [D-Ala2,D-Leu5]enkephalin to block mu and delta interactions, respectively. Labeling patterns differ markedly from those for mu, delta, or kappa receptors. The highest densities (determined by quantitative autoradiography) are found in the medial portion of the nucleus accumbens, amygdaloid nucleus, hippocampal formation, central gray, locus coeruleus, and the parabrachial nuclei. Receptors in these structures could account for the stimulatory, mood-altering, and analgesic properties of the sigma opiates. Although not the most selective sigma opiate ligand, [3H](-)-SKF-10,047 binds to sigma opiate receptors in brain, and this interaction can be readily distinguished from its interactions with other classes of brain opiate receptors.