Golden Shiner Notemigonus crysoleucas× Rudd Scardinius erythrophthalmus Hybrids: Gonad Histology and Spawning Trials

Hybrid fish were produced in ponds by crossing golden shiners × rudd ( Notemigonus crysoleucas × Scardinius erythrophthalmus ) and rudd × golden shiners. Histologically, testes from the hybrids contained spermatocytes that resembled those of the parental species, but no sperm were observed. Lack of sperm in hybrids could have been a seasonal effect. The ovaries of both types of hybrids contained variable numbers of morphologically normal, vitellogenic oocytes and numerous abnormal oocytes in the chromatin nucleolar stage. Abnormal oocytes were necrotic or had irregularly shaped nuclei and clumped chromatin. Many oocyte nests contained infiltrating macrophnges. Spawning trials with F₁ hybrids did not result in spawning behavior or production of F₂ generation fish. Colden shiner × rudd hybrids are of reduced fecundity, but sterility was not conclusively demonstrated.     

Immune production of interferon by cultured peripheral blood mononuclear cells from calves infected with BHV1 and PI3 viruses

Peripheral blood mononuclear cells (PBMC) from calves infected with bovine herpesvirus type 1 (BHV1) or parainfluenza 3 virus (PI3) were cultured in vitro in the presence of inactivated specific antigen presented on MDBK cells. In the presence of inactivated antigen, PBMC from both BHV1-infected and control calves produced interferon (IFN)-alpha in 24 hour cultures. Altering the culture conditions did not result in the detection of immune-specific IFN produced by mononuclear cells from BHV1-infected calves. However, spontaneous IFN was detected in the absence of antigen in 24 hour cultures from infected animals: this IFN was pH 2 labile and completely neutralised by antiserum to recombinant bovine IFN-gamma. Spontaneous IFN-gamma production was only seen in calves following a second BHV1 inoculation, given four to seven weeks after the primary dose. In contrast PBMC cultures from PI3 virus-infected calves did not produce IFN-gamma spontaneously, but did so in cultures which contained inactivated PI3 antigen. Mononuclear cells from control animals failed to produce either IFN-alpha or -gamma when cultured with inactivated PI3 virus. IFN-gamma was detected in PBMC cultures after the primary infection, with no increase in production occurring following subsequent PI3 virus inoculations. Immunospecific production of IFN-gamma provides a simple method for monitoring cell-mediated immunity in BHV1- and PI3 virus-infected calves and can be used for evaluating the efficacy of vaccines against these viruses.     

SIMULTANEOUS DOUBLE-CONTRAST CYSTOGRAPHY AND CYSTOMETRY IN DOGS

Double-contrast cystograms and cystometrograms were performed simultaneously in each of six male and six female dogs with normal urinalyses. The dogs were sedated with oxymorphone and acepromazine. Detrusor reflex occurred in 11 of 12 dogs. After bladder infusion of 0.88 ml/kg of positive-contrast medium, there was mucosal irregularity in eight of 12 dogs and bladder shape distortion in 12 of 12 dogs. Bladder distortion decreased with progressive infusion of CO₂, and mucosal irregularity was eliminated after infusion of 50–100 ml CO₂. The bladder neck in all dogs was initially located within the pelvic canal. In ten of 12 dogs, the bladder neck was cranially displaced when the bladder was fully distended. Bladder wall thickness was approximately 1 mm circumferentially at all degrees of distention. There was no discernible difference between bladder shape prior to and at initiation of contraction. It was concluded that radiographic determination of a normal urinary bladder can be made without complete bladder distention and that cystograms and cystometrograms can be routinely performed simultaneously in dogs in which both procedures are required.     

Evaluation of the long-term oral consequences of equine exodontia in 50 horses

The aims of this study were to objectively evaluate and quantify the process of post-extraction cheek teeth (CT) dental drift in horses, and to report on associated disorders of CT wear and long-term periodontal health. Fifty horses that had CT oral extraction because of apical infection were prospectively re-examined and a full oral examination, including measurements of some dental parameters, was performed.Narrowing of the extraction space was noted in all cases with complete closure occurring in 18% of horses. The rate of dental drift was calculated as 15.7% of extraction space/year (range 4–50%) and was not associated with the age at extraction (P = 0.78) or frequency of dental care since extraction (P = 0.48). There was a significant negative relationship between the rate of dental drift and the duration of time since extraction (P = 0.008). Overgrowths were present on the opposite CT row in 98% of horses, including opposite the extracted CT and on the Triadan 06s and 11s. No significant difference was noted in either the number of diastemata (P = 0.9) or periodontal disease score (P = 0.8) between the extraction and the contralateral cheek tooth rows.     

Influence of surgical margin completeness on risk of local tumour recurrence in canine cutaneous and subcutaneous soft tissue sarcoma: A systematic review and meta‐analysis

The present peer‐reviewed veterinary literature contains conflicting information regarding the impact of surgical margin completeness on risk of local tumour recurrence in canine soft tissue sarcoma (STS). This systematic review and meta‐analysis was designed to answer the clinical question: “Does obtaining microscopically tumour‐free surgical margins reduce risk for local tumour recurrence in canine cutaneous and subcutaneous STS?” A total of 486 citations were screened, 66 of which underwent full‐text evaluation, with 10 studies representing 278 STS excisions ultimately included. Cumulatively, 16/164 (9.8%) of completely excised and 38/114 (33.3%) of incompletely excised STS recurred. Overall relative risk of 0.396 (95% confidence interval = 0.248‐0.632) was calculated for local recurrence in STS excised with complete margins as compared to STS excised with incomplete margins. Risk of bias was judged to be low for all studies in terms of selection bias and detection bias but high for all studies in terms of performance bias and exclusion bias. The results of the present meta‐analysis, coupled with the results of individual previous studies, strongly suggest that microscopically complete surgical margins confer a significantly reduced risk for local tumour recurrence in canine STS. Future studies ideally should adhere to standardized conducting and reporting guidelines to reduce systematic bias.     

The use of traits to interpret responses to large scale - edge effects: a study of epigaeic beetle assemblages across a <Emphasis Type="Italic">Eucalyptus</Emphasis> forest and pine plantation edge

Context

Edge effects due to habitat loss and fragmentation have pervasive impacts on many natural ecosystems worldwide.

Objective

We aimed to explore whether, in tandem with the resource-based model of edge effects, species feeding-guild and flight-capacity can help explain species responses to an edge.

Methods

We used a two-sided edge gradient that extended from 1000 m into native Eucalyptus forest to 316 m into an exotic pine plantation. We used generalised additive models to examine the continuous responses of beetle species, feeding-guild species richness and flight-capable group species richness to the edge gradient and environmental covariates.

Results

Phytophagous species richness was directly related to variation in vegetation along the edge gradient. There were more flight-capable species in Eucalyptus forest and more flightless species in exotic pine plantation. Many individual species exhibited multiple-peaked edge-profiles.

Conclusions

The resource based model for edge effects can be used in tandem with traits such as feeding-guild and flight-capacity to understand drivers of large scale edge responses. Some trait-groups can show generalisable responses that can be linked with drivers such as vegetation richness and habitat structure. Many trait-group responses, however, are less generalisable and not explained by easily measured habitat variables. Difficulties in linking traits with resources along the edge could be due to unmeasured variation and indirect effects. Some species’ responses reached the limits of the edge gradient demonstrating the need to examine edge effects at large scales, such as kilometres.

     

A new approach for rescaling land cover data

The resolution of satellite imagery must often be increased or decreased to fill data gaps or match preexisting project requirements. It is well known that a change in resolution introduces systematic errors of size, shape, location and amount of contiguous land cover types. Nevertheless, robust methods for rescaling landscape data are frequently required to assess patterns of landscape change through time and over large areas. We developed a new method for rescaling spatial data that allows map resolution (grain size) to be either increased or decreased while holding the total proportion of land cover types constant. The method uses a weighted sampling net of variable resolution to sample an existing map and then randomly selects from the frequency of cover types derived from this sample to assign the cover type for the corresponding location in the rescaled map. The properties of the sampling net had a variable effect on measures of landscape pattern with the characteristic patch size (S) the most robust metric and the number of clusters (A) the most variable. A comparison of up-scaled and down-scaled maps showed that this process is not symmetrical, producing different errors for increases versus decreases in grain size. Rescaling Landsat (30 m) imagery to the 10 m resolution of SPOT imagery for four National Park units within Maryland and Virginia resulted in errors due to rescaling that were small (1–2%) relative to the total error (∼11%) associated with these images. The new rescaling method is general because it provides a single method for increasing or decreasing resolution, can be applied to maps with multiple land cover types, allows grid geometry to be transformed (i.e., square to hexagonal grids), and provide a more consistent basis for landscape comparisons when maps must be derived from multiple sources of classified imagery.