Resistance to synthetic pyrethroids in South Australian populations of sheep lice (Bovicola ovis)

SUMMARY Lice were collected from 71 flocks detected as Infested at market Inspection in 1990 and 1991, from 16 flocks where resistance was suspected and from 31 flocks from Kangaroo Island. Susceptibility to cypermethrin was measured by a treated surface technique and survival of lice at 5 ppm or greater was taken as an indication of resistance. The prevalence of resistance was 34% in louse populations from the market inspection sample, 50% in flocks in which resistance was suspected and 68% in flocks from Kangaroo Island. Most resistance factors were in the range 1 to 20 although one louse population with a resistance factor of 91 was found on Kangaroo Island.     

Ex Vivo Comparison of Three Surgical Techniques to Stabilize Canine Cranial Cruciate Ligament Deficient Stifles

Objective— To quantify and compare canine stifle stability after 3 stabilization techniques. Study Design— Randomized controlled study. Sample Population— Adult canine cadaveric pelvic limbs. Methods— Total craniocaudal (CrCa) tibial translation quantified in stifles with the cranial cruciate ligament (CrCL) intact, transected, and stabilized with 1 of 3 techniques: (1) hamstring graft (HG); (2) modified retinacular imbrication (MRIT); (3) anatometric fascia lata translocation (AFLT). Tibial translation was quantified from radiographs generated during application of cranial and caudal forces to the tibia. After removal of all soft tissues except periarticular ligaments and fixation, CrCa tibial translation, as before, and medial–lateral rotation, via torsional loading, was quantified with an active motion analysis system. Total tibial translation was evaluated for effect of technique and cruciate status using mixed effect linear model with significance considered at P‐value <.05. Results— CrCa translation was not significantly different across stabilization techniques with CrCLs intact, transected, or after stabilization. Poststabilization translation was significantly less than posttransection for all techniques. Compared with the intact CrCL, CrCa translation poststabilization after HG was significantly greater whereas poststabilization after MRIT and AFLT was not significantly different. Tibial rotation exceeded instrumentation limits in 62.5% HG limbs, 20% MRIT limbs, and 60% AFLT limbs. Conclusions— All 3 stifle stabilization techniques confer comparable CrCa translational stability after CrCL disruption with that provided by the MRIT and AFLT techniques comparable to the intact CrCL. Clinical Relevance— The extra‐ and intracapsular techniques evaluated in this study reduced CrCa tibial translation in CrCL deficient stifles to varying amounts.     

The status of marine biodiversity in the Eastern Central Atlantic (West and Central Africa)

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Salinity's influence on boron toxicity in broccoli: II. Impacts on boron uptake, uptake mechanisms and tissue ion relations

Limited research has been conducted on the interactive effects of salinity and boron stresses on plants despite their common occurrence in natural systems. The purpose of this research was to determine and quantify the interactive effects of salinity, salt composition and boron on broccoli (Brassica oleracea L.) performance, particularly, element accumulation, ion interactions and boron uptake processes. A greenhouse experiment was conducted using a sand tank system where salinity-B treatment solutions were supplemented with a complete nutrient solution. Chloride-dominated salinity and salinity characteristic of California's San Joaquin valley (SJV), or sulfate-dominated, were tested at ECw (electrical conductivity of the irrigation water) levels of 2, 12 and 19 dS m⁻¹. Each salinity treatment consisted of boron treatments of 0.5, 12 and 24 mg L⁻¹. Salinity, regardless of salt composition, reduced shoot boron concentration at very high boron concentration (24 mg L⁻¹). However, increased salinity increased shoot boron concentration when external boron concentration was low (0.5 mg L⁻¹). Tissue Ca, Mg, Na, K, S and Cl concentrations were also affected by salinity level, chloride or sulfate salinity composition, and in some cases by substrate boron concentration. Calcium concentrations in shoots were greater for chloride-treated salinity as compared to SJV salinity-treated plants; magnesium concentrations trended opposite and were greater in those treated with SJV salinity. Chloride and sodium shoot concentrations both increased with salinity. Shoot chloride was greater with chloride substrate salinity and shoot sodium was greater with SJV substrate salinity. Using stable isotope analysis of solutions to separate transpiration from evapotranspiration (ET), we found that boron uptake and accumulation in the shoot was not simply the product of mass flow (solution concentration × cumulative transpiration), and the vast majority of the water lost from the tank system was by transpiration (>90%) regardless of treatment. Under low substrate boron, the levels of boron in broccoli shoots could be not accounted for by simple passive uptake and transport in the transpiration stream, which suggests that some energy-dependent process was also occurring. However, under high boron treatments, broccoli plants exhibited a mechanism that restricted boron uptake, transport and accumulation in the shoot.     

In vitro amino acid absorption using hydrolysed sardine muscle or soybean meal at different intestinal regions of the Pacific bluefin tuna (Thunnus orientalis)

The amino acid (AA) absorption along the intestinal tract of the Pacific bluefin tuna (Thunnus orientalis) was evaluated using two hydrolysed protein sources (fresh sardine muscle and soybean meal) with the everted intestine technique. Pork pepsin and pancreatic enzyme extract from the bluefin tuna were used to hydrolyse the protein from fresh sardine (FSH) and soybean meal (SMH) under optimal bluefin tuna fish physiological conditions. Both of the hydrolysate solutions were tested within three intestinal sections from the bluefin tuna. The everted intestinal fractions immersed in the hydrolysate solutions were sampled at different times to analyse for AA and absorption rate calculations. Fresh sardine and SMH contained greater amounts of essential amino acids (EAA) than those of non‐essential amino acids (NEAA); however, the profiles of AA absorbed showed higher absorption of NEAA in both cases. Using a similar concentration solution, the absorption rates within the intestinal fractions showed a preferential absorption in the proximal and distal regions for Arg and His when FSH was used. However, the absorption rates for Lys resulted in a decreasing proximal‐to‐distal gradient between the different intestinal regions for FSH and SMH. The possibility of a catabolic role of certain AAs in the enterocytes being able to explain the differences in absorption is discussed.     

Heart regeneration in zebrafish

Cardiac injury in mammals and amphibians typically leads to scarring, with minimal regeneration of heart muscle. Here, we demonstrate histologically that zebrafish fully regenerate hearts within 2 months of 20% ventricular resection. Regeneration occurs through robust proliferation of cardiomyocytes localized at the leading epicardial edge of the new myocardium. The hearts of zebrafish with mutations in the Mps1 mitotic checkpoint kinase, a critical cell cycle regulator, failed to regenerate and formed scars. Thus, injury-induced cardiomyocyte proliferation in zebrafish can overcome scar formation, allowing cardiac muscle regeneration. These findings indicate that zebrafish will be useful for genetically dissecting the molecular mechanisms of cardiac regeneration.     

A virus reveals population structure and recent demographic history of its carnivore host

Directly transmitted parasites often provide substantial information about the temporal and spatial characteristics of host-to-host contact. Here, we demonstrate that a fast-evolving virus (feline immunodeficiency virus, FIV) can reveal details of the contemporary population structure and recent demographic history of its natural wildlife host (Puma concolor) that were not apparent from host genetic data and would be impossible to obtain by other means. We suggest that rapidly evolving pathogens may provide a complementary tool for studying population dynamics of their hosts in "shallow" time.     

Salt sensitivity of cowpea at various growth stages

Summary The relative salt tolerance of cowpea (Vigna unguiculata (L.) Walp. cv. California Buckeye No. 5) at different stages of growth was determined in a greenhouse. Plants were grown in sand cultures that were irrigated four times daily with modified half-strength Hoagland's solution. Salination with NaCl and CaCl₂ (2:1 molar ratio) provided seven treatment solutions with osmotic potentials (_s) ranging from –0.05 to –1.05 MPa (electrical conductivities of 1.4 to 28 dS/m). Salt stress was imposed for 20 days beginning at either 7, 27, or 52 days after planting. The three 20-day stages are referred to here as vegetative, flowering, and pod filling stages. Pod and seed yields from plants stressed during either the vegetative, flowering, or pod-filling stages indicated that cowpea was the most sensitive to salinity during the vegetative stage and became less sensitive the later plants were stressed. Seed yield was reduced 50% at _s =–0.45, –0.76, and –0.88 MPa for plants salinized during the vegetative, flowering, and pod-filling stages, respectively. Salinity reduced seed yield by reducing seed number; it had little, if any, effect on the weight of individual seeds. Vegetative growth was significantly reduced by salt stress during all three stages but the effect was much less when stress was imposed during the last two stages than during the first stage.