Endocrine and metabolic responses of the collared peccary (Tayassu tajacu) to immobilization with ketamine hydrochloride

Serial physiological responses were examined for 150 min from captive collared peccaries during immobilization with ketamine hydrochloride. Rectal temperatures decreased significantly (P less than 0.01) during anesthesia. Serum concentrations of total proteins, albumin, cholesterol, alanine aminotransferase, and calcium declined significantly (P less than 0.05) during the first 45 min post-immobilization before stabilizing. Concentrations of lactate dehydrogenase and alkaline phosphatase in sera showed similar but nonsignificant (P greater than 0.05) trends. Inorganic phosphorus and aspartate aminotransferase concentrations increased significantly (P less than 0.05) throughout the trial. Concentrations of serum glucose and glucocorticoid during the immobilization period were highly variable between individuals. Serum electrolytes, urea nitrogen, creatinine, gammaglutamyl transferase and progesterone were not significantly (P greater than 0.05) affected by immobilization. Elevations in serum testosterone were noted. Results indicated appropriate sampling times relative to immobilization for assay of particular serum biochemicals and steroid hormones during investigations of the physiology of the collared peccary.     

Mating behavior,egg deposition,incubation period,and hatching in the clearnose skate,Raja eglanteria

Synopsis Adult clearnose skates, Raja eglanteria, were captured during the winters of 1981 and 1983, and observed to mate in captivity. Mating and egg depositions take place on the central west coast of Florida from December through mid-May. During copulation the male holds the trailing edge of the female's right or left pectoral fin firmly in his mouth, swings his tail beneath hers and inserts one clasper into the distal end of her reproductive tract. Copulation may last one to four hours during which time sperm pass from the urogenital papilla of the male along the clasper groove to the female. Sperm move cranially to the upper portion of the shell gland where they are stored and remain viable for at least three months. The ovum is fertilized in the shell gland. The egg case bears a prominent projection or horn at each corner. The two posterior ones are shorter and bear tendrils which are covered with a sticky substance that insures attachment to the substrate when the egg is deposited. Fertilized eggs are laid in pairs at intervals ranging from 1 to 13 days (mean of 4.5 ± 2.2 days). As development proceeds within the egg case a plugged slit on the lateral side of each horn opens and permits seawater to wash the developing embryo. Incubation periods for eggs maintained between 20–22°C decrease in duration throughout the egg laying season, ranging from 94 days initially to 77 days for eggs laid later in the spring. At hatching, the anterior end of the egg case ruptures, and the skate emerges abruptly with its pectoral fins rolled dorsally.     

Leakage from Seedling Roots, Inoculated with Phytophthora cinnamomi

A sequential study of electrolyte leakage from roots inoculated with Phytophthora cinnamomi demonstrated changes in leakage in response to infection. These changes may be characterised in terms of susceptibility and resistance. Field resistant species showed two types of response (i) rapid leakage 2—4 h after inoculation, such as in Eucalyptus calophylla, E. maculata and Gahnia radula, (ii) no significant increase in leakage with infection, for example in cereals and in juncus bufonius. Susceptible species, such as Xanthorrhoea australis, E. sieberi and E. marginata showed slow but continually increasing leakage after inoculation, and usually lost significantly more electrolyte than field resistant species. Both electrolyte leakage and susceptibility of two Eucalyptus species varied with root temperature. Roots of both the susceptible and field resistant Eucalyptus species grown at 14°C showed similar leakage patterns to those grown at 24°C although no lesions formed at 14°C. Both amount of leakage and lesion length increased at 28°C. E. marginata (susceptible) lost significantly greater quantities of electrolyte than E. calophylla at each temperature tested. Leakage from artificially wounded roots did not vary with either temperature or with host susceptibility. No significant changes in conductivity were recorded with saprophytic colonization of roots, or with incubation in either low molecular weight culture filtrate or β-glucan solutions. Vacuum infiltration with the culture filtrate or the β-glucan slightly increased initial electrolyte loss in comparison with that of the controls. The increased leakage from infected roots may be toxin mediated or due to enzymie degradation of host plasma membranes, and occurred within the region of the limited lesion in the case of field resistant species, compared with the larger zone of extending necrosis characteristic of susceptible species.     

Localization of the hemagglutinating activity of platelet thrombospondin to a 140 000-dalton thermolytic fragment

The platelet protein thrombospondin (TSP) which is secreted from alpha-granules upon platelet activation agglutinates trypsinized, glutaraldehyde-fixed human erythrocytes. Optimal conditions for the hemagglutinating activity require that both Ca2+ and Mg2+ be present in final concentrations of 2 mM. In the presence of dithiothreitol (i.e., reduction of disulfide bonds), the lectin-like activity decreases in a manner proportional to the extent of reduction of the molecule from its native trimeric configuration into its Mr 180 000 subunits. Proteolysis of purified TSP with thermolysin, which produces discrete domains with the capacity to bind fibrinogen and heparin, also diminishes, but does not abolish, the hemagglutinating activity. Fibrinogen was without effect on hemagglutinating activity while heparin was found to be a potent inhibitor. Other proteoglycans such as hyaluronic acid, chondroitin sulfate, keratan sulfate, dermatan sulfate, and heparan sulfate had no effect. That portion of the TSP molecule apparently responsible for the hemagglutinating activity was identified by incubating a thermolytic digest of TSP with red blood cells and then determining which fragment was bound to the cell surface. The binding site resides within a peptide fragment of 140 000 daltons but is absent from an Mr 120 000 fragment derived from the Mr 140 000 fragment. Under the conditions for optimal expression of hemagglutinating activity (i.e., 2 mM MgCl2 and 2 mM CaCl2), this Mr 140 000 fragment was also shown to have heparin binding activity.     

Dielectric behavior of DNA solution at radio and microwave frequencies (at 20 degrees C).

The dielectric constant and conductivity of calf thymus DNA were investigated at frequencies between 0.1 MHz and 70 GHz. This work is to investigate the dielectric properties of DNA in low gigahertz region and also to study whether the dielectric behavior of the water is affected by the presence of highly charged DNA. The results of these measurements indicate the presence of two anomalous dispersions, the one between 1 MHz and 1 GHz and the second one above 1 GHZ. The dispersion at low frequencies is likely to arise from polar groups in the DNA molecule. The relaxation behavior of unbound water in DNA solution is only slightly affected by the presence of DNA at concentrations below 1%.     

Mechanisms of use-dependent block of sodium channels in excitable membranes by local anesthetics

Many local anesthetics promote reduction in sodium current during repetitive stimulation of excitable membranes. Use-, frequency-, and voltage-dependent responses describe patterns of peak INa when pulse width, pulse frequency, and pulse amplitude are varied. Such responses can be viewed as reflecting voltage-sensitive shifts in equilibrium between conducting, unblocked channels and nonconducting, blocked channels. The modulated-receptor hypothesis postulates shifts in equilibrium as the result of a variable-affinity receptor and modified inactivation gate kinetics in drug-complexed channels. An alternative view considers drug blocking in the absence of these two features. We propose that drug binds to a constant-affinity channel receptor where receptor access is regulated by the channel gates. Specifically, we view channel binding sites as guarded by the channel gate conformation, so that unlike receptors where ligands have continuous access, blocking agent access is variable during the course of an action potential. During the course of an action potential, the m and h gates change conformation in response to transmembrane potential. Conducting channels with both gates open leave the binding site unguarded and thus accessible to drug, whereas nonconducting channels, with gates in the closed conformation, act to restrict drug access to unbound receptors and possibly to trap drug in drug-complexed channels. We develop analytical expressions characterizing guarded receptors as "apparently" variable-affinity binding sites and predicting shifts in "apparent" channel inactivation in the hyperpolarizing direction. These results were confirmed with computer simulations. Furthermore, these results are in quantitative agreement with recent investigations of lidocaine binding in cardiac sodium channels.     

Correlations of understory herb distribution patterns with microhabitats under different tree species in a mixed mesophytic forest

Summary This study examines the role of canopy trees in the formation and maintenance of different herb microhabitats in a mixed mesophytic forest stand. Herb abundance and reproductive success were recorded in 54 circular plots under seven species of canopy trees and in 15 circular control plots>2 m from any tree. Soil moisture, soil nutrient levels, litter depth, and light intensity were measured in a subset of these plots. Ordination of plots by both herb relative abundance and by reproductive success of common species indicated that herb assemblages under most canopy tree species were similar to those away from trees. However, herb assemblages under Fagus grandifolia trees differed moderately from the others while plots under Quercus alba trees supported significantly different herb assemblages. Analyses of variance revealed that several herb species occurred at significantly closer mean distance to the base of Q. alba or Fagus trees or at higher densities under these tree species. Soils around Q. alba trees had significantly higher concentrations of calcium and sulfate ions, and higher pH than plots under other tree species and control plots. This correlated closely with Q. alba stemflow which had higher concentrations of calcium and sulfate ions and lower concentrations of hydrogen ions than stemflow from other trees at this site. The slightly lower soil pH near the base of Fagus trees may have been related to the high volumes of stemflow produced by this species. Stepwise regression showed significant correlations between abundances of five common herb species and soil nutrient patterns. Maintenance of spatial heterogeneity in forest floor resources by the presence of different species of canopy trees may therefore be important in the maintenance of diversity in these understory herb communities.     

In vivo development and pathogenicity of Ascosphaera proliperda (Ascosphaeraceae) to the alfalfa leafcutting bee, Megachile rotundata

First instar larvae of the leafcutting bee, Megachile rotundata, were fed on either artificial or natural provisions containing spores of Ascosphaera proliperda. Two isolates were used as a source of inocula: one originated from in vitro isolates obtained while culturing what was thought to be pure spores of A. aggregata, the second originated from in vitro cultures from Denmark. Histological and scanning electron microscopy studies revealed that the spores germinated in the gut lumen and the developing hyphae invaded all tissues, after which they penetrated through larval integument and began the sexual phase of the life cycle aerially. Virtually all fungus-exposed larvae developed symptoms of disease regardless of source of inoculum, type of provision, and spore dose (1.5 × 10³ to 3 × 10⁶) per insect. It was concluded that the fungus was pathogenic to the alfalfa leafcutting bee under laboratory conditions and future studies should be conducted to determine its etiology, cross infectivity, and natural distribution in other bee taxa.