Occupancy of Random Plots by White-Tailed and Gunnison's Prairie Dogs

ABSTRACT Areas occupied by white-tailed prairie dogs (WTPD; Cynomys leucurus) and Gunnison's prairie dogs (GPD; C. gunnisoni) are not well-known in Colorado (USA) and elsewhere. Suitable methodology for monitoring changes in populations of WTPD and GPD over broad areas also has not been well established. We evaluated occupancy modeling methodology to establish baseline occupancy rates for WTPD and GPD in Colorado. We estimated that WTPD occupied 24.1% (SE = 12.8) of 47,710 0.25-km² plots and GPD occupied 7.5% (SE = 1.3) of 158,225 0.25-km² plots in Colorado during 2004 and 2005. Areas reported as colonies in the Colorado Division of Wildlife's database were not good predictors of WTPD and GPD occupancy. Occupancy rates were highest for GPD at intermediate elevations. We estimated detection probabilities for surveys from the ground of 0.760 (SE = 0.042) for WTPD and 0.786 (SE = 0.060) for GPD. Probability of detection for WTPD improved with lower temperature and earlier Julian date, whereas no covariates improved detection rates for GPD. We recommend that wildlife managers use occupancy monitoring to establish status and trends in populations of WTPD and GPD across their range.     

First Record of the Peritrich Trichodina diaptomiBasson and Van As, 1991 (Protozoa: Ciliophora) on a South American Calanoid Notodiaptomus deitersi (Poppe, 1890) (Crustacea: Copepoda)

ABSTRACT. The ciliate Trichodina was recorded on the calanoid Notodiaptomus deitersi in a shallow, eutrophic reservoir, located in the centre‐west of Brazil. The species was confirmed as Trichodina diaptomi, a species widely distributed in Europe, Africa, Asia and Australia. It was observed moving freely over the carapace of the copepod, and using its adhesive disc. This is the first record for the species in the Americas.     

Portasomes as Coupling Factors in Active Ion Transport and Oxidative Phosphorylation

SYNOPSIS. We propose that particles, 7–15 nm in diameter,observed on the apical plasma membranes of cation transportingcells of insect midgut, salivary glands, and Malpighian tubulesare modified F₁-F₀ coupling complexes such as those found onphosphorylating membranes of mitochondria, chloroplasts, andbacteria. We suggest the generic term, portasome, to describeall of these particles and point out that they are located onthe side of the membrane which is electronegative and has thelow cation concentration, i.e., on the input side in each case.Biophysical evidence identifies the portasome bearing membraneas the ion transporting membrane in several insect epithelia,some of which exhibit ion modulated ATPase activity. The activityof a K⁺-modulated ATPase from Manduca sexta midgut is increasedin portasome enriched plasma membrane fractions. We proposethat portasomes orient the scalar hydrolysis of negatively chargedMgATP^2– to less negatively charged MgADP thereby eliminatingthe attraction of MgATP^2– to K⁺ with the result that theK⁺ ions are ejected to the opposite side of the portasome bearingmembrane. This mechanism explains the coupling of the scalarhydrolysis of ATP to the vectorial active transport of K⁺ whichleads to the establishment of a K⁺ electrochemical gradient.The reverse process, but with an H⁺ ionophore replacing a K⁺ionophore in the portasome, would provide a mechanism for couplingthe vectorial flow of H⁺, driven by a proton electrochemicalgradient, to scalar ATP synthesis and thereby provide a mechanismfor oxidative phosphorylation. Electrogenic active potassiumion transport would appear to have evolved from oxidative phosphorylation.     

Stomatal response to vapour pressure deficit and the effect of plant water stress

Abstract The dynamic response of stomata to changes in atmospheric humidity was investigated in Fragaria × ananassa Duch., Picea engelmannii Parry, and Pseudotsuga menziesii (Mirb.) Franco; and the effect of water stress on this response was determined in Pseudotsuga menziesii. The plants were rotated through three regimes of ambient temperature and vapour pressure deficit: 35°C–3. 5kPa, 35°C–0. 5 kPa, and 20°C–1. 5kPa. Branch and leaflet conductance were measured with a steady-state porometer, first at ambient vapour pressure deficit and then at one of four treatment conditions achieved by increasing or decreasing vapour pressure within the porometer cuvette. All three species showed similar stomatal response: enhanced conductance at low vapour pressure deficit and depressed conductance at high vapour pressure deficit. Engelmann spruce was more sensitive than Douglas fir and strawberry. Plant water status significantly altered stomatal response to vapour pressure deficit. The relationship of conductance of xylem water potential was linear under ambient conditions but became curvilinear when conductance was measured above and below ambient vapour pressure deficit. Between ?0. 5 MPa and ?2. 0 MPa xylem water potential, the stomata were sensitive to vapour pressure deficit, but below ? 2. 0 MPa, the sensitivity decreased.     

Disarticulation patterns in Ordovician crinoids: Implications for the evolutionary history of connective tissue in the Crinoidea

Taphonomic information is examined to evaluate the early history of connective tissues in the Crinoidea. The pattern of stalk segmentation of Middle and Late Ordovician crinoids is consistent with the two-ligament (intercolumnal and through-going ligaments) pattern present in living isocrinid crinoids and interpreted for fossil isocrinids, holocrinids, and Lower Mississippian crinoids. A single rhombiferan was also examined; its taphonomic pattern is also indicative of this style of tissue organization. Furthermore, the taphonomy of all Middle and Late Ordovician crinoids may reflect that they lacked discretely organized muscles between arm brachials, which is consistent with the hypothesis that muscles evolved as a connective tissue between plates only once within the Crinoidea, during the Early Devonian. These data indicate that the two-ligament organization of the stalk is a primitive feature among the Crinoidea and perhaps even among stalked echinoderms. Therefore, the autotomy function of this column-tissue organization among living crinoids is an exaptation. On the other hand, discretely organized muscles as connective tissue in crinoid arms is a derived trait that first appeared during the middle Paleozoic; this adaptation proved very successful for the advanced cladid crinoids.     

Proteolytic activity in the ectoperitrophic fluid of blood-fed Culex nigripalpus

In blood-fed Culex nigripalpus Theobald, proteolytic activity appeared in the ectoperitrophic fluid after 3 h, but only after 6 h in a homogenate of the blood-filled midgut. The activity continued to be higher in ectoperitrophic fluid than in whole gut homogenate until about 40 h after the meal, when most of the intact clot had disappeared. Apparently, undigested blood inhibits proteolytic activity. The blood clot lacked activity and the inhibitor could not be removed by washing. The results are compatible with a hypothesis that the peritrophic membrane separates the digestion from the ingestion compartment.