Generation of a synthetic memory trace

We investigated the effect of activating a competing, artificially generated, neural representation on encoding of contextual fear memory in mice. We used a c-fos-based transgenic approach to introduce the hM(3)D(q) DREADD receptor (designer receptor exclusively activated by designer drug) into neurons naturally activated by sensory experience. Neural activity could then be specifically and inducibly increased in the hM(3)D(q)-expressing neurons by an exogenous ligand. When an ensemble of neurons for one context (ctxA) was artificially activated during conditioning in a distinct second context (ctxB), mice formed a hybrid memory representation. Reactivation of the artificially stimulated network within the conditioning context was required for retrieval of the memory, and the memory was specific for the spatial pattern of neurons artificially activated during learning. Similar stimulation impaired recall when not part of the initial conditioning.     

Conversion of Cortisone to Cortisol and Prostaglandin F2α Production by the Reproductive Tract of Cows at the Late Luteal Stage In Vivo

Previous in vitro studies demonstrated that bovine endometrium has the capacity to convert inactive cortisone to biologically active cortisol (Cr) and that Cr inhibits cytokine‐stimulated prostaglandin F_2α (PGF) production. This study was carried out to test the hypothesis that bovine reproductive tract has the capacity to convert cortisone to Cr in vivo and to evaluate the effects of intravaginal application of exogenous cortisone on uterine PGF secretion during the late luteal stage. The temporal relationships between PGF and Cr levels in uterine plasma were also determined. Catheters were inserted into jugular vein (JV), uterine vein (UV), vena cava caudalis (VCC) and aorta abdominalis (AA) of six cows on Day 15 of the oestrous cycle (ovulation = Day 0) for frequent blood collection. On Day 16, the cows were divided randomly into two groups and infused intravaginally with vaseline gel (10 ml; control; n = 3) or cortisone dissolved in vaseline gel (100 mg; n = 3). Blood samples were collected at ?2, ?1, ?0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h after treatments (0 h). Intravaginal application of cortisone increased plasma concentrations of Cr between 0.5 and 1.5 h in UV, at 0.5 h in VCC, at 1 h in JV and at 1.5 h in AA. The plasma concentrations of PGF in UV and of PGF metabolite in JV were greater at 0.5 and 1 h in the cortisone‐treated animals than in control animals. The levels of PGF in UV blood plasma decreased after Cr reached its highest levels. The overall findings suggest that the female reproductive tract has the capacity to convert cortisone to Cr in vivo. Based on the temporal changes of PGF and Cr levels in the uterine plasma, a biphasic response in PGF secretion was found to be associated to the Cr increase induced by the cortisone treatment at the late luteal stage in non‐pregnant cows.     

Controlling disease outbreaks in wildlife using limited culling: modelling classical swine fever incursions in wild pigs in Australia

ABSTRACT: Disease modelling is one approach for providing new insights into wildlife disease epidemiology. This paper describes a spatio-temporal, stochastic, susceptible- exposed-infected-recovered process model that simulates the potential spread of classical swine fever through a documented, large and free living wild pig population following a simulated incursion. The study area (300 000 km2) was in northern Australia. Published data on wild pig ecology from Australia, and international Classical Swine Fever data was used to parameterise the model. Sensitivity analyses revealed that herd density (best estimate 1-3 pigs km-2), daily herd movement distances (best estimate approximately 1 km), probability of infection transmission between herds (best estimate 0.75) and disease related herd mortality (best estimate 42%) were highly influential on epidemic size but that extraordinary movements of pigs and the yearly home range size of a pig herd were not. CSF generally established (98% of simulations) following a single point introduction. CSF spread at approximately 9 km2 per day with low incidence rates (< 2 herds per day) in an epidemic wave along contiguous habitat for several years, before dying out (when the epidemic arrived at the end of a contiguous sub-population or at a low density wild pig area). The low incidence rate indicates that surveillance for wildlife disease epidemics caused by short lived infections will be most efficient when surveillance is based on detection and investigation of clinical events, although this may not always be practical. Epidemics could be contained and eradicated with culling (aerial shooting) or vaccination when these were adequately implemented. It was apparent that the spatial structure, ecology and behaviour of wild populations must be accounted for during disease management in wildlife. An important finding was that it may only be necessary to cull or vaccinate relatively small proportions of a population to successfully contain and eradicate some wildlife disease epidemics.     

Simulation of foot-and-mouth disease spread within an integrated livestock system in Texas, USA

We used a simulation study to assess the impact of an incursion of foot-and-mouth disease (FMD) virus on the livestock industries in an 8-county area of the Panhandle region of Texas, USA. The study was conducted in a high-density livestock area, with an estimated number of cattle on-feed of approximately 1.8 million. We modified an existing stochastic, spatial simulation model to simulate 64 scenarios for planning and decision-making. Our scenarios simulated four different herd types for the index herd (company feedlot, backgrounder feedlot, large beef, backyard) and variations in three mitigation strategies (time-of-detection, vaccine availability, and surveillance during disease control). Under our assumptions about availability of resources to manage an outbreak, median epidemic lengths in the scenarios with commercial feedlot, backgrounder feedlot, large beef and backyard index herd types ranged from 28 to 52, 19 to 39, 18 to 32, and 18 to 36 days, respectively, and the average number of herds depopulated ranged from 4 to 101, 2 to 29, 1 to 15 and 1 to 18, respectively. Early detection of FMD in the index herd had the largest impact on reducing (13–21 days) the length of epidemics and the number of herds (5–34) depopulated. Although most predicted epidemics lasted only 1–2 months, and <100 herds needed to be depopulated, large outbreaks lasting 8–9 months with up to 230 herds depopulated might occur.     

Effects of Matrix Filtration of Low-Quality Boar Semen Doses on Sperm Quality

The aim of this work was to develop a method to enhance the sperm parameters of ejaculates with low sperm quality from Piétrain boars. Seminal doses were filtered through columns of DEAE Sephadex (length 2.5 ± 0.5 cm), CM Sephadex (length 5 ± 0.5 cm), glass wool (length 2 ± 0.5 cm) or glass bead (length 10 ± 0.5 cm), with an exit flow rate of 1 ml/40 s in all cases. For each male, 10 ml of the sperm cell-rich fraction diluted at 1 : 6 were filtered. Sperm quality was assessed before and after filtration. Sperm morphology, sperm motility and sperm concentration were determined using the computer program sca ^® 2002 Production, and sperm viability was evaluated by fluorescence multistaining. Osmotic resistance test and hyperosmotic resistance test were used to determine the osmotic resistance of spermatozoa, whereas l -lactate production estimated the metabolic activity. Results showed a decrease of sperm concentration and osmotic resistance of spermatozoa after filtration in the four matrixes. However, an increase in the frequency of viable spermatozoa with intact acrosome after filtration in glass bead columns and an increase of morphologically normal spermatozoa after filtration in Sephadex CM-50, glass wool and glass bead columns were observed. Despite the decrease in the frequency of progressive motile spermatozoa, l -lactate production and mitochondrial sheath integrity maintained constant after filtration. Our findings indicate that column filtration is an effective method to enhance the sperm quality by selecting viable and morphologically normal spermatozoa without altering DNA, plasma membrane, mitochondrial sheath integrity or inducing premature acrosome reaction.     

Gross,histologic, and immunohistochemical characteristics of cutaneous chromatophoromas in captive bearded dragons

Chromatophoromas are neoplasms that develop from the dermal pigment-bearing and light-reflecting cells (chromatophores) in the skin of reptiles, fish, and amphibians. Seventeen cutaneous chromatophoromas were identified from 851 bearded dragon submissions (2%) to a private diagnostic laboratory in a 15-y period. No sex predilection was found. Ages ranged from 9 mo to 11 y. Chromatophoromas most commonly were single, raised, variably pigmented masses or pigmented scales on the trunk, and less commonly the extremities or head. Microscopically, iridophoromas, melanophoromas, mixed chromatophoromas, and nonpigmented chromatophoromas were identified. Neoplasms were often ulcerated and invaded deep into the subcutis and muscle. Most commonly, nuclear atypia was mild-to-moderate, and mitotic count was low. Six neoplasms had abundant, periodic acid-Schiff–positive, mucinous stroma. Histologic examination was often adequate to diagnose chromatophoromas in bearded dragons given that 11 of 17 had some degree of pigmentation, although it was often scant. IHC for S100 and PNL2 could be helpful to diagnose poorly pigmented neoplasms. No lymphatic invasion or metastases at the time of excision were noted in any of the cases. Follow-up data were available for 6 cases, with no reports of recurrence or neoplasia-related death. Two cases had elevated mitotic counts and nuclear pleomorphism, which has been associated with metastasis in other reports of bearded dragon chromatophoromas. In general, it appears that aggressive surgical excision is often curative, but monitoring may be warranted for cases in which tumors had high mitotic count and nuclear pleomorphism.     

Renal myxozoanosis in crowned river turtles Hardella thurjii: description of the putative agent Myxidium hardella n. sp. by histopathology, electron microscopy, and DNA sequencing

Chelonian myxozoanosis is rarely reported and has previously not been documented to cause disease. This report describes myxozoanosis associated with significant renal disease in two Crowned River turtles (Hardella thurjii). One turtle presented with emaciation and died. The cage mate presented with emaciation and was euthanized. Histologically, renal intratubular myxozoan spores were associated with renal tubular necrosis, tubular mineralization, and chronic interstitial nephritis, with membranoproliferative and mes-angioproliferative glomerulopathy. Both turtles also had disseminated metastatic mineralization. On the basis of these findings, chronic renal insufficiency from myxozoanosis and subsequent metastatic mineralization were considered the primary problems. By light and electron microscopy, the myxozoan spores had features of the genus Myxidium. Maximum parsimony analysis of small-subunit rDNA sequences placed the turtle myxozoan basal to a clade containing Myxidium truttae and a Myxidium sp. with strong bootstrap support. This myxozoan agent appears to be a significant pathogen in H. thurjii on the basis of morphologic changes in the kidneys of in the infected turtles.     

Use of laser rhinoscopy to treat a nasal obstruction in a captive California sea lion (Zalophus californianus).

Laser rhinoscopy was used to treat a nasal obstruction in a captive California sea lion (Zalophus californianus). The rehabilitated, adult, female sea lion developed mucopurulent, intermittent, bilateral nasal discharge and functional nasal obstruction 20 mo after acquisition by the Aquarium of the Pacific in Long Beach, California. A 3-mm-thick soft tissue structure spanning the region between the soft and hard palates, a deviated nasal septum, and several nasopharyngeal polyps were identified. Biopsies and cultures of the obstructive web showed ulcerative granulation tissue with suppurative inflammation, bacterial infection, and a partial section of an arthropod larva (not speciated). Laser rhinoscopy was performed to relieve the caudal nasopharyngeal obstruction and ablate the polyps. The sea lion appeared to breathe through the nares with lessened nasal discharge for a period of 6 wk after laser therapy, but within 8 wk the mucopurulent nasal discharge returned, the obstruction had reformed, and the sea lion was euthanized. Postmortem examination confirmed antemortem diagnoses of caudal nasopharyngeal obstruction secondary to inflammatory tissue; however, no additional sections of arthropod parasites were located microscopically.