Which behavior does the lamprey central motor program mediate?

The isolated lamprey spinal cord, when bathed in 2 millimolar D-glutamic acid, will generate a pattern of motor neuron discharge that has generally been assumed to represent the central motor program for swimming. Motion pictures of behaving lampreys were analyzed by a computer algorithm to estimate undulatory movement parameters that could be directly compared with those generated during D-glutamate--induced undulations. The D-glutamate--induced movement parameters were significantly different from those observed during normal behaviors, including swimming, but accurately predicted the undulations produced by spinally transected adult lampreys.     

Ecological forecasts: an emerging imperative

Planning and decision-making can be improved by access to reliable forecasts of ecosystem state, ecosystem services, and natural capital. Availability of new data sets, together with progress in computation and statistics, will increase our ability to forecast ecosystem change. An agenda that would lead toward a capacity to produce, evaluate, and communicate forecasts of critical ecosystem services requires a process that engages scientists and decision-makers. Interdisciplinary linkages are necessary because of the climate and societal controls on ecosystems, the feedbacks involving social change, and the decision-making relevance of forecasts.     

Nitrogen fixation in the marine environment

Cyanobacteria of the genus Oscillatoria (Trichodesmium) account for annual inputs of nitrogen to the world's oceans of about 4.8 x 10(12) grams while benthic environments contribute 15 x 10(12) grams. The sum of these inputs is one-fifth of current estimates of nitrogen fixation in terrestrial environments and one-half of the present rate of industrial synthesis of ammonia. When the total of all nitrogen inputs to the sea is compared with estimated losses through denitrification, the marine nitrogen cycle approximates a steady state. Oceanic nitrogen fixation can supply less than 0.3 percent of the calculated demand of marine phytoplankton. The minor contribution by nitrogen fixation to the overall nitrogen economy of the sea is not consistent with the supposition that nitrogen is the primary limiting nutrient and suggests that factors other than nitrogen availability limit phytoplankton growth rates.     

Antiphosphotyrosine recovery of phospholipase C activity after EGF treatment of A-431 cells

A tenfold increase in phospholipase C activity specific for phosphatidylinositol 4,5-bisphosphate (PIP2) was immunopurified from extracts of A-431 epidermoid carcinoma cells stimulated with epidermal growth factor. This finding suggests a biochemical link between growth factor-stimulated tyrosine kinase activity and PIP2 hydrolysis.     

Effect of Transgene Introduction and Recloning on Efficiency of Porcine Transgenic Cloned Embryo Production In Vitro

Retrovirus-mediated exogenous gene transfection of somatic cells is an efficient method to produce transgenic embryos by somatic cell nuclear transfer (SCNT). This study evaluated whether efficiency of transgenic embryos production, by SCNT using fibroblast cells transfected by retrovirus vector, is influenced by the introduced transgene and whether recloning could further improve its efficiency. Transgenic cloned embryos were produced by SCNT of porcine foetal fibroblast cells transfected by either LNβ-Z or LNβ-enhanced green fluorescent protein (EGFP) retrovirus vector and evaluated for their developmental ability in vitro . Blastomeres from four-cell stage porcine embryos, produced by SCNT of foetal fibroblast cells transfected with LNβ-EGFP retroviral vector, were subsequently recloned into enucleated metaphase II oocytes and evaluated for changes in chromatin configuration, in vitro embryo development and gene expression. Analysis of results showed that cleavage and blastocyst rates of porcine SCNT embryos, using LacZ (53.6 ± 6.4%; 12.0 ± 5.7%) or EGFP (57.5 ± 6.3%; 10.1 ± 4.1%) transfected fibroblasts, did not differ (p > 0.05) from those of non-transfected controls (60.9 ± 8.2%; 12.3 ± 4.0%). Recloning of blastomeres did not further improve the in vitro development rate. Interestingly, the nuclei of blastomere underwent slower remodelling process than somatic cell nuclei. Both cloned and recloned embryos showed 100% transgene expression and there were no evidence of mosaicism. In conclusion, our data shows that the efficiency of transgenic cloned embryos production by SCNT of somatic cells transfected with replication-defective retrovirus vector is not influenced by the transgene introduction into donor cells and recloning of four-cell stage blastomere could not further improve its efficiency.     

Localization of immunoglobulins and complement by the peroxidase antiperoxidase method in autoimmune and non-autoimmune canine dermatopathies

Formalin-fixed, paraffin embedded skin biopsy specimens from 44 dogs with various dermatopathies were examined for the presence of immunoglobulins (IgG, IgM, IgA) and complement (C3) by the peroxidase antiperoxidase method (PAP). Final diagnoses of the skin diseases were determined by clinical findings, fungal and bacterial cultures, skin scrapings, serum endocrinologic tests, and histologic features of cutaneous biopsies. The dermatopathies included examples of pyoderma (folliculitis/furunculosis), demodecosis, sarcoptic mange, dermatophytosis, endocrine dermatopathy, and autoimmune skin disease (AISD). In the latter category, 7 cases of pemphigus foliaceus, 1 pemphigus vulgaris, 4 discoid lupus erythematosus (DLE) and 4 examples of indeterminate AISD were examined. Immunoglobulins, C3, or both, were localized in tissue sections from AISD (15/16), pyoderma (7/11), demodecosis (4/8) sarcoptic mange (3/3), and dermatomycosis (2/3). Endocrine dermatopathy biopsies were consistently negative for Ig and C3 (0/3). The pattern of localization was most often intercellular (31/44 positive biopsies) with basement membrane immunoreactivity in 4 cases of DLE, and 1 case of indeterminate AISD. There was no consistent correlation between histologic features of hematoxylin and eosin-stained biopsies and the presence of Ig and C3. Clinical outcome was similar in both Ig and C3 positive and negative cases of non-AISD dermatitis. The high percentage (95%) of positive results in AISD biopsies indicates the usefulness and sensitivity of the PAP method for the localization of Ig and C3. Because of the high percentage of Ig localization in pyoderma (73%), biopsy specimens with extensive inflammatory skin disease are not suitable for diagnosis of AISD. The PAP method is useful in the diagnosis of AISD in biopsy specimens with minimal inflammation. Caution is warranted in the interpretation of immunoreactivity independent of clinical and histologic information.