THE EFFECT OF PREPUBERAL AND POSTPUBERAL GONADECTOMY ON RADIAL PHYSEAL CLOSURE IN MALE AND FEMALE DOMESTIC CATS

Male (n=6/group) and female (n=6/group) kittens were gonadectomized at 7 weeks (prepuberally) or 7 months of age (postpuberally), or left intact. Lateral radiographic projections of the right forelimb were made from 4 months of age until the distal radial physis was closed, or 24 months of age. In males, distal radial physeal closure was delayed in both groups of gonadectomized animals, compared to intact males (p<0.01). In females, proximal radial physeal closure was significantly delayed in prepuberally gonadectomized animals (p=0.02), and distal radial physeal closure was significantly delayed in both groups of gonadectomized animals, compared to intact animals (p<0.01). Final radial length (females p<0.01, males p=0.01), and age and radial length at time of the growth plateau (p<0.01) were significantly increased in all gonadectomized animals. Age at gonadectomy had no effect on age and radial length at time of the growth plateau. No puberal growth spurt was observed in any of the cats.     

Squirrel poxvirus: Landscape scale strategies for managing disease threat

Squirrel poxvirus (SQPV) is a well-documented example of pathogen-mediated competition between an invasive species, the grey squirrel (Sciurus carolinensis), and a native species, the Eurasian red squirrel (Sciurus vulgaris). SQPV causes disease with high mortality in red squirrels but appears non-pathogenic in grey squirrels. Not all populations of introduced grey squirrels carry the virus, notably those in Scotland and Italy, and the rate of red squirrel replacement by grey squirrels is some twenty times faster in those areas where grey squirrels carry the virus. Here we develop strategies to manage the SQPV disease threat to red squirrels by reference to the largest, designated red squirrel refuge site in England, Kielder Forest (50 000 ha). Using modelling techniques, we identify four main corridors within the buffer zone by which grey squirrels will reach Kielder, initially within two years and in large numbers within 10 years. Assuming that greys will not settle within Kielder because of the unfavourable nature of the spruce habitat, we predict that SQPV disease will burn out at the edges of the forest, although many red squirrels will die. This burn-out is unlikely to be the scenario in other refuge areas where the habitat is more favourable to greys. We conclude that the conservation of red squirrels will depend on minimising contact between red and grey squirrel populations, and we advocate monitoring grey squirrels in corridors within buffer zones around refuge areas, and removing them when detected.     

Systematic conservation planning products for land-use planning: Interpretation for implementation

There is an obvious need to incorporate biodiversity concerns into the policies and practices of sectors that operate outside protected areas, especially given the widespread devolution of power to local (municipal) authorities regarding land-use decision-making. Consequently, it is essential that we develop systematic (target-driven) conservation planning products that are both user-friendly and user-useful for local government officials, their consultants and the elected decision makers. Here, we describe a systematic conservation planning assessment for South Africa’s Subtropical Thicket Biome that considered implementation opportunities and constraints from the outset by developing - with stakeholders - products (maps and guidelines) that could be readily used for local government land-use planning. The assessment, with concomitant stakeholder input, developed (i) Megaconservancy Networks, which are large-scale conservation corridors of multiple ownership that achieve targets principally for biodiversity processes; (ii) conservation status categories (critically endangered, endangered, vulnerable, currently not vulnerable) for all biodiversity features, identified on the basis of available extant habitat to achieve conservation targets, and (iii) a conservation priority map which integrates (i) and (ii). This map was further interpreted for municipal-level decision-makers by way of corresponding guidelines for land-use in each of the conservation status categories. To improve general awareness of the value of biodiversity and its services, a handbook was compiled, which also introduced new and impending environmental legislation. Within 18 months of the production of these products, evidence of the effective integration, or mainstreaming, of the map and its guidelines into land-use planning has been encouraging. However, more effort on increasing awareness of the value of biodiversity and its services among many stakeholder groups is still required. Nonetheless, our approach of planning for implementation by considering the needs and obligations of end users has already yielded positive outcomes. We conclude by providing suggestions for further improving our approach.     

Volume Contents

Volume Contents

Volume Contents     

鸡球虫的疫苗控制及其流行病学检测的新手段

球虫病是由顶复器门艾美耳属的几种细胞内寄生原虫引起的 ,是造成现代养禽业经济损失最大的疾病之一。该病是由 7种艾美耳球虫 (通常是几种混合感染 )在肠道内反复发生无性或有性繁殖所致 ,虽然球虫病在集约化养禽场临床感染相对较少 ,但亚临床感染却非常普遍。在集约化养鸡场 (尤其是肉鸡生产上 ) ,控制艾美耳球虫感染主要通过饲料中添加药物预防 ,但活弱毒苗或强毒苗免疫也起作用。过去几年 ,在欧洲范围内 ,肉种鸡饲养使用较安全的虫苗已相当重要。而且可以预测 ,许多养禽国家如欧盟的一些国家 ,活致弱毒苗作为替代抗球虫药的主流 ,其影响…     

Enzyme variation and pathogenicity of recent field isolates of Eimeria tenella

Seventy isolates of Eimeria tenella, obtained from commercial poultry farms worldwide and four reference laboratory strains were characterised by studies on the electrophoretic mobility of up to three enzymes. All populations possessed the same electrophoretic form of lactate dehydrogenase and malate dehydrogenase and one of two forms of glucose phosphate isomerase. One isolate was characterised by both forms of glucose phosphate isomerase. Studies on several isolates indicated that there was no correlation between the form of glucose phosphate isomerase found and the pathogenicity of an isolate.     

Immunoassays and biosensors for monitoring environmental and human exposure to pyrethroid insecticides

This paper describes some of the early work on pyrethroid insecticides in the Casida laboratory and briefly reviews the development and application of immunochemical approaches for the detection of pyrethroid insecticides and their metabolites for monitoring environmental and human exposure. Multiple technologies can be combined to enhance the sensitivity and speed of immunochemical analysis. The pyrethroid assays are used to illustrate the use of some of these immunoreagents such as antibodies, competitive mimics, and novel binding agents such as phage-displayed peptides. The paper also illustrates reporters such as fluorescent dyes, chemiluminescent compounds, and luminescent lanthanide nanoparticles, as well as the application of magnetic separation, and automatic instrumental systems, biosensors, and novel immunological technologies. These new technologies alone and in combination result in an improved ability to both determine if effective levels of pyrethroids are being used in the field and evaluate possible contamination.     

A close-up look at Io from Galileo's near-infrared mapping spectrometer

Infrared spectral images of Jupiter's volcanic moon Io, acquired during the October and November 1999 and February 2000 flybys of the Galileo spacecraft, were used to study the thermal structure and sulfur dioxide distribution of active volcanoes. Loki Patera, the solar system's most powerful known volcano, exhibits large expanses of dark, cooling lava on its caldera floor. Prometheus, the site of long-lived plume activity, has two major areas of thermal emission, which support ideas of plume migration. Sulfur dioxide deposits were mapped at local scales and show a more complex relationship to surface colors than previously thought, indicating the presence of other sulfur compounds.     

Effect of varying dietary lipid and protein levels on growth and reproductive performance of female swordtails Xiphophorus helleri (Poeciliidae)

We conducted a study to determine the effect of dietary protein and lipid levels on the growth and reproductive performance of a freshwater ornamental species, the swordtail (Xiphophorus helleri). Two protein levels (20% and 30%) with four lipid levels (8%, 12%, 16%, 20%) within each protein levels were tested through formulation of practical diets labelled as 20P8L, 20P12L, 20P16L, 20P20L, 30P8L, 30P12L, 30P16L and 30P20L respectively. Results showed that dietary protein level significantly influenced final weight, weight gain and specific growth rate, while dietary lipid did not influence any of these growth parameters. More specifically, increasing dietary lipid levels from 8% to 12–16% in both 20% and 30% protein levels significantly improved swordtail growth performance. Dietary protein levels positively influenced gonadosomatic and hepatosomatic indexes. Both dietary protein and lipid significantly influenced female muscle protein content. Significantly highest fry production was obtained from diets 30P12L and 30P16L, respectively, while diet 20P8L resulted in the lowest fry production. This present study indicates the dietary protein and lipid requirements for female swordtails for optimized growth and reproductive performances to be at 30% and 12% respectively.