Spatial variability of common carp populations in relation to lake morphology and physicochemical parameters in the upper Midwest United States

Weber MJ, Brown ML, Willis DW. Spatial variability of common carp populations in relation to lake morphology and physicochemical parameters in the upper Midwest United States.
Ecology of Freshwater Fish 2010: 19: 555–565. © 2010 John Wiley & Sons A/S Abstract – Common carp (Cyprinus carpio) is a widespread invasive species that is tolerant of a wide range of environmental conditions. Despite the circumpolar distribution of the species, limited information is available describing factors related to spatial variation in population characteristics. Eighty‐four lakes and impoundments in the upper Midwest United States were sampled to investigate the relationships of common carp relative abundance with size structure, condition and growth rates. We also investigated abiotic factors (lake morphology, physical solids and water quality) that may broadly influence common carp populations. Common carp size structure and condition were inversely related to relative abundance. Common carp relative abundance increased and size structure shifted to smaller individuals with increased lake depth, whereas lake surface area, watershed:surface area ratio and physical solids were also important in explaining common carp abundance and size structure. Common carp condition was best explained by water quality parameters and increased with metrics of lake productivity. We conclude that knowledge of factors associated with variation in common carp populations among lakes provides insights into the autecology and broad provisions for management of this generalist invasive species.     

Prevalence of chronic wasting in Dutch dairy herds with a history of chronic health problems

The prevalence of chronic wasting in cattle in March and April 2000 was studied on 218 dairy farms with a history of health problems accompanied by wasting, following reports in the media suggesting that chronic wasting was a substantial problem on Dutch dairy farms. A telephone call revealed that the health problems had resolved on 41 farms; 16 of these farms had culled all cattle. Two farmers refused co-operation. On the remaining 175 farms the animals were inspected and was completed a questionnaire. A high percentage of culling for of health reasons (on average 18.1% of young stock and adult cattle) and an increased mortality rate (4.8%) were reported on the farms visited. In only two of the 175 inspected herds, more than 20 percent of cattle were found showing signs of wasting. These two herds were identified as 'chronic wasting herds'. The prevalence of such herds was low in this study. Consequently, it is likely that there were very few 'chronic wasting herds' among the whole Dutch dairy population in March/April 2000.     

Clostridium septicum myositis in a western lowland gorilla (Gorilla gorilla gorilla).

A 10-yr-old male gorilla (Gorilla gorilla gorilla) with a history of conspecific bite wounds was evaluated for acute onset of depression, anorexia, and right hemiparesis. The animal was immobilized for diagnostic examination and treatment for suspected toxic shock from a necrotizing, emphysematous wound infection, but was euthanized due to complications during recovery. Gross and histopathologic examination revealed acute necrotizing myositis, fasciitis, cellulitis, and emphysema in the affected wound area, with large numbers of large Gram-positive rods among necrotic muscle fibers. Severe pulmonary edema with airways containing fibrin, acute hemorrhage in multiple body sites, thrombosis in blood vessels in the skeletal muscle, liver, and lung, and lymph node hyperplasia with lymphoid necrosis and hemorrhage. Immunohistochemical fluorescent antibody staining of muscle from the wound site was positive for     

Digalacturonates from pectin degradation induce tissue responses against potato soft rot

The pathogenicity of the bacteriumErwinia carotovorasubsp.atroseptica, which causes potato soft rot, is triggered by short oligogalacturonates released by enzymic degradation of plant cell wall pectin. In the first stage unsaturated digalacturonate (uDG), produced by the action of pectate lyases, is degraded by oligogalacturonide lyase (OGL) to keto-deoxyuronate (DKI). The OGL encoding gene fromE. carotovoraand the corresponding recombinant enzyme were characterized. Measuring the changes in plant cell viability and tissue maceration during soft rot pathogenesis in tissue slices of sprouting potato tubers, it was observed that exposure to uDG and DKI, produced by recombinant OGL, killed up to 30% of the plant cells over a period of 16h. This protected the tissue against maceration byE. carotovorasubsp.atroseptica. Endogenous OGL activity was detected in extracts from sprouting tubers where it may be involved in the conversion of uDG into cell toxic compounds. The results indicate that an additional function of small, diffusable digalacturonates is to induce plant cell death during the rotting process, thus contributing to defence reactions againstE. carotovorasubsp.atroseptica.     

Crossbreeding among British and continental European dual-purpose breeds in the coastal Pacific Northwest

From 1979 through 1987, British breed and crossbred cows were mated to Simmental, Pinzgauer or Tarentaise bulls or to Hereford-Angus crossbred bulls. Beginning in 1982, continental European crossbred females also entered the herd, to be mated for first calving to Hereford-Angus or Angus bulls and as cows to continental European or Hereford-Angus bulls. In progeny of British breed and crossbred cows, dam breed effects on birth and weaning weight were not important, but continental European crossbred calves were heavier than British crossbred contemporaries at birth and weaning. Pinzgauer- and Simmental-sired calves were heavier at birth than Tarentaise crosses, but calves sired by each of the continental breeds had similar weaning weights. Maternal heterosis was greater than direct heterosis effects on weaning weight (8% vs 5%), but only direct heterosis (13%) influenced birth weight. Within progeny of continental European crossbred cows, calves with a Tarentaise maternal grandsire were lighter at birth, with no significant difference among other maternal grandsire breeds. Maternal breed effects on weaning weight were not significant. Nevertheless, in contemporary years, continental European crossbred cows reared calves that were 10% heavier than calves reared by British crossbred cows. Pacific Northwestern cattle producers could achieve substantial increases in weaning weight from introducing inheritance from continental European dual-purpose breeds into cow herds and calf crops of British ancestry.     

Combination of polyacrylamide gel electrophoresis with enzyme-linked immunosorbent assay: A simple method for determination of antibody specificity and detection of antigens in complex mixtures

Complex antigenic mixtures were separated on polyacrylamide gels in the presence of SDS. After electrophoresis, the gels were cut into equal fractions. Antigens were eluted from the fractions and could be bound to different solid phases on which a conventional enzyme-linked immunosorbent assay was performed. Antibody binding fractions could then be related with the bands of a stained gel run in parallel. This technique proved to be fast and sensitive. Antigens present in nanogram amounts in individual fractions were sufficient for the detection of specific antibody. We describe here the application of this technique to antibodies specific of parasite, viral, bacterial and mycoplasmal antigens and to antibodies against hormones and a muscle protein.     

Use of an immortalized bovine mammary epithelial cell line (MAC-T) to measure the mitogenic activity of extracts from heifer mammary tissue: effects of nutrition and ovariectomy

The objectives of the experiment were (1) to determine whether MAC-T cells would accurately mimic the previously observed proliferative responses of primary mammary epithelial cells (MEC) to mammary tissue extracts from high and low-fed heifers and (2) to determine whether mammary tissue extracts from ovariectomized (OVX) heifers would have lower mitogenic activity than intact controls. Addition of mammary tissue extracts to cell culture media of MAC-T cells plated on plastic or collagen-coated plastic to a range of concentrations between 1 and 8% resulted in dose-dependent increases in cell proliferation. Furthermore, mammary tissue extracts from low-fed prepubertal heifers aged 9 months, stimulated significantly more proliferation of MAC-T cells, as measured by 3H-thymidine incorporation into DNA than mammary tissue extracts from high-fed heifers (40.6 cpm x 10(3) per well versus 21.9+/-1.8 cpm x 10(3) per well). These observations suggested that MAC-T cells would be a suitable alternative to primary MECs for measuring the mitogenic activity of mammary tissue extracts. Conversely, no difference was observed in the mitogenic activity of mammary tissue extracts from OVX or control heifers. Possibly, MAC-T cells provide a good model for nutrition- but not ovarian-induced changes in mammary growth. Alternatively, that reduction of in vivo mammary development following OVX did not result in reduced mitogenic activity of the mammary tissue extracts emphasizes that heifer mammary development is the result of complex interactions between local growth factors and systemic hormones.