Effects of dietary cadmium chloride throughout gestation on blood and tissue metabolites of primigravid and neonatal dairy cattle.

Thirty-six postpubertal Holstein heifers were allocated to three groups and fed the same diet, which differed only in the concentration of Cd: control group (.25 ppm of Cd), low-Cd group (1 ppm of Cd), and high-Cd group (5 ppm of Cd). Cadmium was supplemented to the low-Cd and high-Cd groups using CdCl2. Liver, kidney cortex, and abdominal muscle were biopsied for mineral analysis from one-half of the heifers of each group before Cd supplementation and again from the same animals within 5 d after parturition, 394 d later. Blood, liver, and muscle were collected from each calf within 5 h after birth. In the dam, 5 ppm of dietary Cd caused a 62-, 27-, and 4-fold increase in Cd of the kidney, liver, and muscle, respectively; kidney Zn and Fe increased (76%) and decreased (33%), respectively, whereas the serum Cu was reduced (31%). Liver Cu was reduced to 40 and 17% by dietary Cd of 1 and 5 ppm, respectively, in the dams. Calves from dams consuming 5 ppm of Cd had a 29 and 43% reduction in liver Cu and Zn, respectively. In these same calves, packed cell volume, hemoglobin concentration, and serum Cu were decreased by 17, 18, and 25%, respectively, whereas serum Zn was increased (55%). Serum sodium and potassium were reduced by 4 and 13%, respectively, and blood urea nitrogen was increased by 63% in calves from dams consuming 5 ppm of Cd. Feeding primigravid dairy cattle up to 5 ppm of Cd as CdCl2 throughout gestation did not influence the concentration of Cd in the neonate but caused reductions in liver Cu and Zn; teratogenesis was not apparent.     

Zinc bioavailability in feed-grade sources of zinc

Chick bioassays were used to assess bioavailability of zinc (Zn) from inorganic Zn sources. A soy isolate-dextrose diet containing 13 mg Zn/kg diet was supplemented with feed-grade sources of ZnSO4.H2O (ZnSO4) or ZnO and fed for 2 wk after a 7-d Zn-depletion protest period. Bioavailability of Zn in ZnO relative to ZnSO4 (set at 100%) was determined by multiple regression slope-ratio methodology, using both growth and tibia Zn accumulation in chicks fed graded levels of ZnO and ZnSO4. Linear responses for gain and tibia Zn occurred at dietary Zn levels (ZnSO4.7H2O) between 13 mg/kg (basal) and 33 mg/kg (gain) or 53 mg/kg (total tibia Zn). Therefore, two bioavailability assays were conducted using supplemental Zn levels of 0, 7.5 and 15 mg/kg from each Zn source. When weight gain was regressed on supplemental Zn intake, bioavailability of Zn in ZnO was only 61.2% (P less than .01) that of ZnSO4. When total tibia Zn was regressed on supplemental Zn intake, bioavailability of Zn compared with ZnSO4 (set at 100.0%) was 44.1% (P less than .001) for ZnO. With chicks fed soy-based diets, bioavailability of Zn from ZnO was less than that of ZnSO4.     

Unusual osteochondral lesions of the talus in a horse

A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed lateromedial radiographic views identified three discrete semicircular lytic lesions at the proximal articular margin of the medial trochlear ridge of the talus. Conservative management of the lesions was associated with a successful return to racing. The location and appearance of the osteochondral lesions of this report have not been previously reported and may be a manifestation of developmental orthopaedic disease and abnormal endochondral ossification. Nuclear scintigraphy and flexed lateromedial radiographic views facilitated identification of the lesions. This radiographic view is recommended when lameness is isolated to the tarsocrural joint and standard radio-graphic projections fail to identify a cause.     

The landscape ecology of large disturbances in the design and management of nature reserves

Large disturbances such as fires and floods are landscape processes that may alter the structure of landscapes in nature reserves. Landscape structure may in turn influence the viability of species and the functioning of ecosystems. Past reserve design and management strategies have been focussed on species and ecosystems rather than on landscape-scale processes, such as disturbance.An essential feature of a natural disturbance regime is the variation in disturbance attributes (e.g., size, timing, intensity, spatial location). Although some past reserve management policies have included natural disturbances, perpetuating disturbance variation has not been the explicit goal of either reserve design or management.To design a reserve to perpetuate the natural disturbance process requires consideration of: (1) the size of the reserve in relation to maximum expected disturbance size, (2) the location of the reserve in relation to favored disturbance initiation and export zones and in relation to spatial variation in the disturbance regime, and (3) the feasibility of disturbance control at reserve boundaries, or in reserve buffers.Disturbance management possibilities are constrained by the design of the reserve and the reserve goals. Where a natural disturbance regime is not feasible, then it is important that the managed disturbance regime mimic historical variation in disturbance sizes and other attributes as well as possible. Manipulating structure on the landscape scale to restore landscapes thought to have been altered by historical disturbance control is premature given our understanding of spatial disturbance processes in landscapes.     

Subpopulations of Stromal Cells from Long-term Human Bone Marrow Cultures: Ontogeny of Progenitor Cells and Expression of Growth Hormone Receptors *

Long-term culture of bone marrow derived stromal colony forming cells (S-CFC) in matrix and nutrient defined agar medium resulted in stromal cell colonies that pass sequentially through three distinct morphological stages: firstly, aggregated loose syncytium of round to ovoid cells (stage I), a second developmental stage of large branching colonies in which the cells become enlarged, elongated with cytoplasmic projections forming a loosely anastomized network with adjacent cells (stage II), and finally cells become dissociated, loosing their long, thin cytoplasmic filaments and breaking their contacts with one another, but remain large and retain a bi-polar nature (stage III). Cells were also grown in liquid medium in a culture microenvironment closely resembling conditions of haemopoiesis in vitro. Using a panel of well defined monoclonal antibodies reactive against the rat, rabbit and human growth hormone receptors, this study found immunochemical evidence of the presence and localization of binding sites of growth hormone (GH) in the cell membrane and extra-nuclear Golgi area of long-term bone marrow derived human stromal cells in liquid and semi-solid nutrient agar mediums. GH-receptor immunoreactivity was present in small proliferating progenitor cells, myofibroblast-like cells, large reticular fibroblast cells, adipocytes and endothelial cells. Only MAb known to be reactive against human tissue resulted in strong immunoreactivity. The expression of GH-receptors not only on small proliferating, but also on the well differentiated cells, indicates a role for growth hormone on non-progenitor cells. GH-receptor immunoreactivity on differentiating and/or differentiated cells suggests that GH is also necessary for, or has a trophic function in differentiation. We propose that direct GH action is necessary not only for differentiation of progenitor cells as implied by the dual effector hypothesis, but also their subsequent clonal expansion, differentiation and maintenance.     

Comparative Field Performance of Tissue Culture-Derived Lines and Breeder Lines of HY320 Spring Wheat

This study examines the performance of somaclonal spring wheat (Triticum aestivum L.) lines developed through culture of somatic embryos. Twenty-nine breeder lines of the spring wheat cv. ‘HY320’ were compared to 51 somaclonal lines of the same cultivar. Somaclonal lines were derived from 27 individual embryos (with up to four lines in each “family”). Somaclonal and breeder lines were evaluated in five field experiments in western Canada. Somaclonal lines were more variable than breeder lines for most agronomic, yield component and quality characters, suggesting that variability among somaclonal lines resulted partly from the tissue culture process. Somaclonal lines yielded, on average, 11 % less than breeder lines. Somaclonal lines had 3.8 % fewer spikelets per spike, 6.5 % fewer kernels per spike and kernels which were 2.7 % lighter. Somaclonal lines had greater test weight, protein concentration, and sedimentation values, and harder kernels.     

Different sex phenotypes of Cucumis sativus L. and C. melo L. and their endogenous gibberellin activity

Summary Gibberellins were extracted from seeds and green plants of different sex types of the closely related species Cucumis sativus L. (cucumber) and C. melo L. (muskmelon). Both seeds and green plants of monoecious and andromonoecious lines of C. sativus contained significantly higher gibberellin levels at all growth stages tested than did a gynoecious line. Gibberellin activity in the monoecious and andromonoecious C. sativus line reached a maximum at the growth stage corresponding to flower differentiation at cotyledonary and first leaf axils. Vernalization of seeds of gynoecious plants resulted in increased male tendency correlated with increased gibberellin activity. In contrast, monoecious and andromonoecious lines of C. melo were gibberellin deficient relative to hermaphroditic and gynoecious lines.Journal Article No 5534 from the Michigan Agricultural Experiment Station. This work was supported by a grant from the Herman Frasch Foundation.     

Fluorescence Tracing of Diffuse Landfill Leachate Contamination in Rivers

Landfill leachates are composed of a complex mixture of degradation products which include a wide range of potentially fluorescent organic molecules and compounds. Here we investigate the use of fluorescence excitation–emission matrix (EEM) analysis in detecting diffuse landfill leachate contamination in rivers. Landfill leachates from three unlined landfill sites adjacent to our study river are characterised by intense fluorescence at excitation wavelength 220–230 nm, and emission wavelength 340–370 nm, which derives from fluorescent components of the xenobiotic organic matter fraction. Seven surface water sample sites on an adjacent polluted river system were analysed for fluorescence and water quality properties. The 220–230 nm excitation wavelength, 340–370 nm emission wavelength fluorescent centre was also detected in this river system at the sample locations downstream of the landfills, but not at upstream control sites, demonstrating its use as a tracer of landfill leachate contamination. Negative correlations are observed between this fluorescence centre and dissolved oxygen in the river water samples, demonstrating the water quality implications of leachate contamination at this study site. The fluorescence intensity at the 220–230 nm excitation wavelength, 340–370 nm emission wavelength fluorescent centre in landfill leachates is such that it remains detectable at dilutions of 10²–10³, and the fluorescence EEM technique is rapid and cost-effective for use by river managers and water quality regulators.     

Aluminum toxicity to fish in acidic waters

An important consequence of acidification is the mobilization of Al from the edaphic to the aquatic environment. Elevated Al levels in acidic waters may be toxic to fish. Eggs, larvae, and postlarvae of white suckers (Catostomus commersoni) and brook trout (Salvelinus fontinalis) were exposed in laboratory bioassays to pH levels 4.2 to 5.6 and inorganic Al concentrations of 0 to 0.5 mg l^?1. Aluminum toxicity varied with both pH and life history stage. At low pH levels (4.2 to 4.8), the presence of Al (up 0.2 mg l^?1 for white suckers; 0.5 mg l^?1 for brook trout) was beneficial to egg survival through the eyed stage. In contrast, Al concentrations of 0.1 mg l^?1 (for white suckers) or 0.2 mg l^?1 (for brook trout) and greater resulted in measurable reductions in survival and growth of larvae and postlarvae at all pH levels (4.2 to 5.6). Aluminum was most toxic in over-saturated solutions at pH levels 5.2 to 5.4. The simultaneous increase in Al concentration with elevated acidity must be considered to accurately assess the potential effect of acidification of surface waters on survival of fish populations.     

Sediment acid neutralization in softwater lakes

Acid neutralizing capacities (ANC) of sediments from McCloud Lake, Florida and seven other lakes in Wisconsin and Florida were as high as 10 meq 100 g^?1 over the pH range 4.5 to 5.5 in well-mixed batch experiments. Exchange of Ca²⁺ and Mg²⁺ accounted for over 50% of the neutralizing capacity; Al solubilization and sulfate adsorption were unimportant in neutralizing H⁺ additions. ANC was correlated with sediment volatile solids content. Sulfate reduction occurred in microcosms that simulated lake-water interactions and subsurface seepage;in situ pore water profiles and a whole-lake mass balance confirm the occurrence of this process in McCloud Lake. Sediment neutralization is important for lakes that receive most of their water from precipitation and thus are particularly susceptible to acidification.