Extensive dispersal of Roanoke logperch (Percina rex) inferred from genetic marker data

The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (N_e) for a population of Roanoke logperch Percina rex, an endangered darter (Percidae). Juveniles and candidate parents were sampled for 2 years at sites throughout the Roanoke River watershed. Dispersal was inferred via genetic assignment tests (ATs), pedigree reconstruction (PR) and estimation of lifetime dispersal distance under a genetic isolation‐by‐distance model. Estimates of N_e varied from 105 to 1218 individuals, depending on the estimation method. Based on PR, polygamy was frequent in parents of both sexes, with individuals spawning with an average of 2.4 mates. The sample contained 61 half‐sibling pairs, but only one parent–offspring pair and no full‐sib pairs, which limited our ability to discriminate natal dispersal of juveniles from breeding dispersal of their parents between spawning events. Nonetheless, all methods indicated extensive dispersal. The AT indicated unrestricted dispersal among sites ≤15 km apart, while siblings inferred by the PR were captured an average of 14 km and up to 55 km apart. Model‐based estimates of median lifetime dispersal distance (6–24 km, depending on assumptions) bracketed AT and PR estimates, indicating that widely dispersed individuals do, on average, contribute to gene flow. Extensive dispersal of P. rex suggests that darters and other small benthic stream fishes may be unexpectedly mobile. Monitoring and management activities for such populations should encompass entire watersheds to fully capture population dynamics.     

Accumulation of sorghum phytoalexins induced by Colletotrichum graminicola at the infection site

Microspectrophotometry was performed on intact, pigmented vesicle-like inclusions within living sorghum cells that were accumulating phytoalexins as a response to attempted fungal infection. The results indicate that the deoxyanthocyanidin phytoalexins are present in inclusions. Moreover, the phytoalexin concentration within a single inclusion, based on luteolinidin, was calculated to be 0·15 m. The amounts of luteolinidin and apigeninidin in cells involved in the phytoalexin response at individual infection sites were also determined. The data showed that luteolinidin accumulated to levels of 0·48–1·20 ng/cell whereas apigeninidin accumulated to levels of 0·24–0·91 ng/cell. The results of both analyses confirmed that at the infection site the deoxyanthocyanidins accumulate to levels in substantial excess of those required for inhibition of the fungus Colletotrichum graminicola.     

Identity and pathogenicity of Rhizoctonia spp. associated with bare patch disease of cereals at a field site in Western Australia

Roots of seedlings of wheat and barley affected by bare patch disease at a field site in Western Australia were assessed for root damage and plated to isolate fungi. The patches were variable in shape and size and had the most severely affected plants in the centre. Of the 165 isolates ofRhizoctonia spp. obtained, 90% were multinucleate and 10% binucleate, the former being predominant in the plants at the centre of the patch. The relative frequency of binucleate isolates increased with proximity to the periphery. The increase in activity of avirulent binucleate isolates towards the periphery of the patch may be related to the sharp and abrupt edging of the patch. A variety of other species of fungi such asFusarium spp.,Mortierella spp.,Bipolaris sorokiniana, Pythium sp. andTrichoderma sp. were encountered within the patches. The multinucleate isolates belonging to anastomosis groups (Ag) 2–1, 2–2 and 8 (Thanatephorus cucumeris) were most pathogenic to wheat. The binucleate isolates of Ag C, D, E, and K (Ceratobasidium sp.) were less pathogenic. It is suggested that the bare patch disease is caused by a complex of root rot fungi composed of one or more anastomosis groups ofRhizoctonia spp. and other associated fungi.Samenvatting Van kiemplanten van tarwe en gerst, afkomstig van een met kale-plekkenziekte besmet perceel in West Australië werd de mate van wortelbeschadiging bepaald en werden schimmels uit de wortels geïsoleerd. De plekken waren verschillend van vorm en afmeting; de zwaarst aangetaste planten werden in het centrum ervan aangetroffen. Van de 165 verkregen isolaten vanRhizoctonia spp. was 90% meerkernig en 10% tweekernig. De meerkernige overheersten in de centra van de plekken. Relatief gezien nam het aantal tweekernige isolaten toe naarmate de herkomst dichter bij de periferie van de plekken was. De scherpe begrenzing van de ziekte aan de randen van de plekken zou in verband kunnen staan met het toenemen van de activiteit van de avirulente tweekernige isolaten in de nabijheid van de periferie van de plekken. Een aantal andere schimmels, zoalsFusarium spp.,Mortierella spp.,Bipolaris sorokiniana, Pythium sp. enTrichoderma sp. werd eveneens in de plekken aangetroffen. De meerkernige isolaten die tot de anastomosegroepen Ag 2–1, 2–2 en 8 (Thanatephorus cucumeris) behoren, waren voor tarwe het meest pathogeen. De tweekernige isolaten van de anastomosegroepen Ag C, D, E en K (Ceratobasidium sp.) waren minder pathogeen. Gesuggereerd wordt, dat de kale-plekkenziekte veroorzaakt wordt door een complex van verschillende wortelschimmels, die behoren tot een of meer anastomosegroepen vanR. solani en andere daarmee geassocieerde schimmels.     

A multicenter, matched case-control study of risk factors for equine laminitis

Risk factors for equine laminitis were examined in a prospective case-control study of the 258 cases seen at six collaborating veterinary teaching hospitals over a 32-month period. Case-control pairs were matched on institution, clinician, and season of diagnosis. The 90% of case-control pairs (78 acute, 155 chronic) that had complete data for age, gender, and breed were used in separate conditional logistic-regression models for acute and chronic laminitis. There was an increase in risk for horses with acute laminitis from 5 to 7 years of age (OR 4.7, 95% CI 1.3–16) and from 13 to 31 years of age (OR 3.9, 95% CI 1.3–12) (both compared to <5 years); risk was increased for chronic laminitis from 10 to 14 years (OR 3, 95% CI 1.4–6.8) and from 15 to 38 years (OR 2.9, 95% CI 1.4–6.1) (both compared to <6 years). Mares — but not stallions — were more likely than geldings to develop acute laminitis (OR 2.6, 95% CI 1.1–6.2) and chronic laminitis (OR 2.0, 95% CI 1.1–3.6). In the small acute-laminitis data set, the breed variable was collapsed into three categories: Thoroughbred (THB, reference), the Quarter Horse (QH), and other (non-QH-THB). The non-QH-THB group was at increased risk of acute laminitis (OR 3.8, 95% CI 1.2–11.8). For the seven breed-group categories used in the chronic-laminitis model, however, all non-THB breed groups appeared significantly at risk as compared to the THB, with odds ratios ranging from 3.3 (95% CI 1.3–8.30) for the QH to 9.1 (95% CI 2.1–39.3) for ponies.     

Assessment of changes in blood volume in response to resuscitative fluid administration in dogs

Objective: To determine the continuous changes in blood volume in response to fluid administration using an in‐line hematocrit monitor. Design: Prospective study. Setting: Research laboratory. Animals: Four healthy dogs. Interventions: Each dog received intravenous boluses of 80 mL/kg of 0.9% saline (S), 4 mL/kg of 7.5% saline (HS), 20 mL/kg of dextran 70 (D), 20 mL/kg of hetastarch (HES), or no fluids (control, C) on separate occasions. Fluids were administered at 150 mL/min in the S, D, and HES groups, and at 1 mL/kg/min in the HS group. Measurements and main results: Blood volume changes were measured every 20 seconds for 240 minutes using an in‐line hematocrit monitor. There was a rapid rise in blood volume during all infusions. Immediately after the administration of crystalloid fluids, the rapid rise in blood volume ceased. Subsequently, there was a steep decline in blood volume for 10 minutes, and a slower decline thereafter. In contrast, the rise in blood volume continued for at least 10 minutes after the infusion of the colloids was complete, and a plateau was observed for the remainder of the experiment. The blood volume effect, as measured by area under the curve, was significantly greater in the saline group than the other groups during the infusion time and for the 0–240 minutes time period. The areas under the curve for the two colloid solutions were not significantly different from each other during any time periods. The percent increase in blood volume immediately following the infusions was 76.4±10.0 in the S group, 17.1±3.2 in the HS group, 23.0±10.5 in the D group, and 27.2±6.4 in the HES group. At 30 minutes from the start of the infusion, the mean percent increases in blood volumes were 35.2±9.3 in the S group, 12.3±0.9 in the HS group, 35.9±7.3 in the D group, and 36.8±6.5 in the HES group. At 240 h post‐infusion, the mean percent increases in blood volume were 18.0±9.7 in the S group, 2.9±6.1 in the HS group, 25.6±16.1 in the D group, and 26.6±8.6 in the HES group. The C group had a mean percent change in blood volume of ?3.7±3.4 at the end of the experiment. Conclusions: This study indicates that the rapid administration of saline at clinically relevant doses leads to the largest immediate increase in blood volume, although this change is transient because of rapid redistribution of the fluid. Despite a brief increase in blood volume that was almost 3 times the volume administered, hypertonic saline led to the smallest increase in blood volume post‐infusion. The synthetic colloid solutions increased the blood volume by an amount greater than that infused and the effect was sustained for a longer period of time than seen following crystalloid administration, but the maximum increase in blood volume was significantly less than saline. The measurement of continuous changes in blood volume, using an in‐line hematocrit monitor, was a useful means of assessing the dynamic effects of fluid administration in dogs in a research setting.     

Porphyric insecticides. IV: Structure-activity study of substituted phenanthrolines

The porphyric-insecticide-modulating activities of 1,10-phenanthroline and eight of its analogs were investigated. The insecticidal efficacy of these compounds was closely associated with their ability to enhance the conversion of exogenous δ-aminolevulinic acid (ALA) to protoporphyrin IX (Proto). As observed for photodynamic herbicidal effects in plants, the presence of nitrogen atoms at positions 1 and 10 of the macrocycle was essential for porphyric insecticidal activity. This was evidenced by the very limited activity of phenanthrene, in which positions 1 and 10 are occupied by carbon instead of nitrogen atoms. On the other hand, enhancement of Proto formation and porphyric insecticidal activity were maintained following methyl, chloro and nitro group substitution at the periphery of 1,10-phenanthroline. In contrast, Proto levels and photodynamic toxicity were reduced by hydroxy and phenyl substitution at the same positions. Benzyl substitution at the 2–3 and 8–9 positions was also inhibitory. Quantitative structure-activity calculations suggested a relationship between peripheral group substitution and physicochemical properties of the substituted compounds. Electron density changes in 1,10-phenanthroline and its analogs that appeared to be related to reduced efficacy included (a) appearance of positive charge-binding volumes at positions 4 and 7 of the 1,10-phenanthroline macrocycle, which flanks positive charge-repelling volumes, (b) a dramatic increase in superdelocalisability (i.e. electron density) over some unoccupied molecular orbitals, and (c) electronic charge at positions 1 and 10 of the macrocycle. Large increases in van der Waals volumes also exerted negative effects on insecticidal efficacy.     

Intraocular melanoma in an alpaca

A case of primary intraocular melanoma in an alpaca is reported. This patient also presented with a mild normocytic, normochromic anemia and hypoproteinemia. These can be markers of an immunodeficiency syndrome associated with llamas. Although this patient did not appear to have clinical signs of this syndrome, its presence needed to be ruled out as animals affected with this syndrome are subject to recurrent severe debilitating diseases and death. To our knowledge, intraocular melanoma has not been previously reported in an alpaca.     

Acute tracheal obstruction associated with anticoagulant rodenticide intoxication in a dog

An adult female neutered crossbred dog was referred in respiratory distress. Thoracic radiographs revealed tracheal narrowing with a soft tissue opacity dorsal to the trachea, near the thoracic inlet, and a patchy interstitial pulmonary infiltrate. The tracheal narrowing was thought to be due to a combination of intraluminal haemorrhage and mediastinal haemorrhage resulting from a coagulopathy caused by anticoagulant rodenticide intoxication. Treatment included supportive care and administration of vitamin K1, and the dog showed a complete resolution of the clinical signs.