Showing papers on "Animal mortality published in 1991"

Life and death beneath macrophyte canopies: effects of understory kelps on growth rates and survival of marine, benthic suspension feeders.

Abstract: Experiments conducted on rocky bottoms at 7–11 m depth in the San Juan Archipelago, Washington assessed effects of canopies of understory kelps on growth of benthic suspension feeders, determined the mechanisms responsible for effects, and assessed the influence of kelp canopies on survivorship of benthic fauna. Kelp canopics influenced growth rates of diverse suspension feeders. At several sites the musselMytilus edulis, the barnacleBalanus glandula, and the serpulid polychaetePseudochitinopoma occidentalis grew faster on the bottom beneath kelp canopies than on nearby exposed substrata. The cheilostome bryozoanMembranipora membranacea showed a mixed response to kelp canopies, growing faster in exposed regions at one site, but faster beneath canopies at another. There were no differences in growth of 2 other species (the cheilostome bryozoanCheilopora praelonga and the spongeMyxilla incrustans) between kelp and no-kelp treatments; however, some processes influenced by plant canopies affected their growth. Specific mechanisms responsible for kelp effects on growth were assessed in a series of field experiments usingPseudochitinopoma, Membranipora, Cheilopora andMyxilla. Particulate deposition on the bottom, which is more intense beneath canopies, negatively affected growth of all 4 species. Kelps also reduced rates of flow and prevented devented development of microalgal turfs beneath the canopy.Pseudochitinopoma grew faster in the weaker flows below canopies and bothCheilopora andMyxilla grew faster where there were no microalgal turfs. These other effects of kelp canopies were at least as important to growth (in the cases ofCheilopora andMyxilla) or more important to growth (in the case ofPseudochitinopoma) than were the general, deleterious effects of higher sedimentation beneath canopies. The lower growth rates caused by higher sedimentation beneath kelp canopies did not result in higher rates of animal mortality. Surprisingly, kelp canopies typically did not influence mortality due to predation. For 7 of 12 taxa, mortality rates did not differ between kelp-covered and exposed treatments. Significantly higher mortality occurred outside canopies for only 4 of 12 taxa, and for at least 2 of these 4 differences probably were not related to predation.Mytilus, a species rare at these depths, exhibited higher mortality beneath kelp canopies due to predation by crabs. Other macrophytes in fresh and salt water, as well as some benthic animals that create complex, 3-dimensional habitats, should influence benthic organisms and assemblages in ways analogous to the kelps acting through their effects on flow, particle transport, and shading.

Selection of an attenuated Coxsackievirus B3 variant, using a monoclonal antibody reactive to myocyte antigen.

Abstract: Previously, we described a heart-reactive monoclonal antibody (MAb), 10A1, derived from a coxsackievirus B3 (CVB3)-infected mouse. This MAb selectively inhibits infection of HeLa cells and myocytes with the myocarditic virus variant (CVB3W). A plaque-purified variant (H3) of CVB3W was isolated from the heart of an infected animal, and a second virus (H3-10A1) was obtained by growing H3 in HeLa cells in the presence of MAb 10A1. As with the parental CVB3W virus, H3 infection of HeLa cells can be inhibited by MAb 10A1, but the antibody-selected H3-10A1 variant is resistant to MAb inhibition (presumably an escape mutant). BALB/c mice infected with 10(6) PFU of CVB3W, H3, or H3-10A1 resulted in approximately 90% animal mortality with CVB3W or H3 and less than 10% mortality with H3-10A1, suggesting that the escape mutant is less pathogenic. Additionally, hearts from animals infected with H3-10A1 demonstrated only half the amount of myocarditis observed in either CVB3W- or H3-infected mice. Cardiac virus titers were also reduced approximately 200-fold in H3-10A1-infected animals compared with those in mice given the pathogenic variants. In vitro studies indicate that H3-10A1 is less effective in inhibiting cellular RNA and protein synthesis and show reduced virus replication compared with that of pathogenic viruses in cultured myocytes.

A mathematical model for radiation-induced myelopoiesis.

Abstract: A model for damage, repair, killing, and repopulation of myelopoietic marrow is presented. Evaluation produces time and dose-rate profiles during and following any complex irradiation. Equations model variable dose rates, multiple exposures, different sources, and arbitrary intervals between treatments. If factors which dominate the control of biological processes can be demonstrated, an option is to set biological rate constants to experimentally determined values. Previously, knowledge did not permit identification of dominating biological processes and their temporal rates. But a unique feature of this study is that unspecified lesions for killing and injury of cells are evaluated from mortality data on the animal species of choice. "Unspecified'" is used to indicate a condition of assumption-free modeling of molecular processes, whereby rate constants for cellular effects are simply computed directly from animal mortality data. Coefficients (estimated by maximum-likelihood methods for nonspecific proc...

Den Collapse Kills Female Polar Bear and Two Newborn Cubs

Abstract: A female polar bear ( Ursus maritimus ) and two newborn cubs were found dead at their den site on the Yukon coast. The site investigation and necropsy indicated that den collapse was the cause of death. Key words: polar bear, Ursus maritimus , den collapse, mortality, Yukon coast

Ofloxacin and penicillin G combination therapy in prevention of bacterial translocation and animal mortality after irradiation.

Abstract: The efficacies of 40 mg of ofloxacin per kg/day given orally and 250 mg of penicillin per kg/day given intramuscularly, alone or in combination, were evaluated in the prevention of mortality of C3H/HeN female mice given 8.2 Gy of 60Co radiation. Mortalities were 51 of 60 mice (85%) in the control group, 46 of 60 mice (77%) among those treated with penicillin, 32 of 60 mice (53%) among those treated with ofloxacin (P less than 0.05), and 5 of 60 mice (8%) among those treated with ofloxacin and penicillin (P less than 0.001). The organisms recovered from the livers of control mice were members of the family Enterobacteriaceae and Streptococcus spp. A reduction in the number of the Enterobacteriaceae was noted only in ofloxacin-treated mice, and a reduction in the number of Streptococcus spp. was noted only in the penicillin-treated mice. Reductions in the numbers of both groups of organisms were noted only in the animals treated with both agents. This study shows the advantage of the combination of ofloxacin and penicillin in the prevention of bacterial translocation and animal mortality after irradiation.

Altered radioprotective properties of interleukin Iα (IL-1) in non-hematologic tumor-bearing animals

Abstract: The radioprotective properties of IL-1 were investigated in the respective murine hosts for the Lewis lung (LLca) and EMT-6 tumors. For these studies, doses of total body irradiation were selected for the C57B1/6 (9.5 Gy) and Balb/c (7.5 Gy) mice that resulted in a 60% mortality over a 30-day interval. When a "priming" dose of 2.5 × 10 5 U IL-1 was administered 24 hr prior to the radiation exposure, animal mortality was markedly reduced (60% vs 5–10%). Under identical experimental conditions, however, the presence of either the LLca or the EMT-6 tumors in their respective host strains was found to compromise the level of radioprotection conferred by this priming dose of IL-1. In Balb/c mice bearing the EMT-6 tumor, a priming dose of IL-1 resulted in only a modest level of radioprotection when compared to non-tumor-bearing control animals (median animal survival increased by 11.5 days). In C57B1/6 mice bearing the LLca tumor, IL-1 failed to demonstrate any evidence of radioprotection. Following a sublethal dose of total body irradiation, the appearance of an accelerated repopulation of the stem cell (8d CFUs and CFU-GEMM) and the myeloid progenitor (CFU-M) compartments in the marrow of the IL-1 primed EMT-6, but not the LLca, tumor-bearing animals was consistent with the hypothesis that the mechanism leading to radioprotection in IL-I primed rodents involves an accelerated recovery of hematopoietic activity. It was also noted that the presence of the EMT-6 tumor was associated with an increase in the "radiosensitivity" of the Balb/c mouse. Collectively, these data suggest that the use of biological modifiers should be examined under altered physiological conditions prior to attempting to translate them into the clinic.

Remote Sensing of Sea Surface Temperatures for Aquaculture Planning in Northern Norway

Abstract: A major limitation for salmon ( Salmo salar L.) farming in arctic environments is the low winter temperatures influencing the salmon's growth rates, mortality and quality. A detailed knowledge of the sea temperature variations in a region can help to avoid the establishment of fish farms in areas that are less suitable. In order to supply local fish farmers and planning authorities with such information, a satellite survey of sea surface temperatures in a late winter situation was conducted in northern Norway. Landsat Thematic Mapper data were calibrated with in situ measurements. The relationship between sea surface temperatures and other factors in the physical environment was visualized in a very comprehensive way. Temperature zones were found to be consistent with information in literature and of relevance to the fish farming industry. New, potentially suitable sites for fish farming could be indicated in many areas where no historical data were available. Key words: remote sensing, sea surface temperatures, aquaculture planning, northern Norway