Flow cytometric analysis of nuclear DNA content,mitotic chromosome number and protein separation by SDS-PAGE in three accessions of African locust bean (<Emphasis Type="Italic">Parkia biglobosa</Emphasis> Benth.)

Nuclear DNA of three accessions of Parkia biglobosa collected from three locations in northern Cross River State was investigated using a Patec PA II flow cytometer equipped with an argon ion laser (488 nm), and pictures of mitotic chromosomes were taken using a digital micro-camera (Canon) placed on the eye piece of a binocular microscope at 100X oil immersion. Metaphase chromosome counts of 2n = 22 for accessions A and C and 2n = 24 for accession B, were obtained and through flow cytometry, the three accessions were confirmed to be diploids. The nuclear DNA content and genome size for the accessions were 1.5085, 1.489, and 1.5266 pg (737.7054, 728.121, and 746.5074 Mbp) for accessions A, B, and C, respectively. In another experiment, leaf samples from greenhouse-germinated seeds were analyzed for variation in the banding pattern of the protein by SDS-PAGE in the three accessions. Protein was resolved into three banding groups according to their electrophoretic mobility: slow, medium, and fast, clustering between 100–200, 40–70, and 10–25 kDa, respectively. There was 76% similarity in the banding pattern between the accessions.     

Lymphocyte stimulation: transfer of cellular hypersensitivity to antigen in vitro

Tuberculin-sensitive human lymphocytes cultured for 36 hours with tuberculin elaborate a soluble material which causes nonsensitive lymphocytes to respond to tuberculin in vitro by transformation and proliferation.     

A persistent oxygen anomaly reveals the fate of spilled methane in the deep Gulf of Mexico

Methane was the most abundant hydrocarbon released during the 2010 Deepwater Horizon oil spill in the Gulf of Mexico. Beyond relevancy to this anthropogenic event, this methane release simulates a rapid and relatively short-term natural release from hydrates into deep water. Based on methane and oxygen distributions measured at 207 stations throughout the affected region, we find that within ~120 days from the onset of release ~3.0 × 10(10) to 3.9 × 10(10) moles of oxygen were respired, primarily by methanotrophs, and left behind a residual microbial community containing methanotrophic bacteria. We suggest that a vigorous deepwater bacterial bloom respired nearly all the released methane within this time, and that by analogy, large-scale releases of methane from hydrate in the deep ocean are likely to be met by a similarly rapid methanotrophic response.     

Toxicology of selected pesticides, drugs, and chemicals. Pyrethrin and pyrethroid insecticides

Pyrethroids have a wide spectrum of insecticidal potency, vertebrate toxicity, and environmental stability. The exceptionally high selectivity ratios of pyrethrins and pyrethroids have resulted in their use for insect control in numerous formulations. A primary effect of pyrethroids is to slow the closing of the sodium activation gate in nerve cells. All pyrethroids have essentially the same basic mechanism of action on voltage-dependent sodium channels but differ in the magnitude of effect. Based on clinical signs, electrophysiologic responses, and chemical structure, pyrethroids can be classified as Type I or Type II. Inhibition of the GABAA receptor appears to be an additional mechanism of Type II pyrethroids. Clinical signs in small animals during a pyrethroid toxicosis vary but are generally attributable to neural dysfunction. Treatment consists of decontamination procedures and application of appropriate symptomatic care, including control of seizures if necessary.     

Acute intravascular hemolysis in the black rhinoceros: erythrocyte enzymes and metabolic intermediates

Enzymes of aerobic and anaerobic glycolysis, glutathione cycling, and nucleotide metabolism were assayed on erythrocytes from 7 healthy rhinoceroses, 2 rhinoceroses during periods of intravascular hemolysis, and 1 rhinoceros without clinical signs of illness, which was the mother of 3 offspring with intravascular hemolytic syndrome. Measurements also were made of erythrocyte concentrations of glycolytic intermediates, adenine nucleotides, and glutathione. Although comparison of results for healthy and affected rhinoceroses did not identify an enzyme abnormality as a cause for the hemolytic syndrome, the data provided information regarding the metabolic characteristics of erythrocytes from healthy rhinoceroses.     

Systems thinking and practices in the education of agriculturalists

A systems approach has been taken to a review of agricultural education programmes and as the essential theme of resultant curricula at Hawkesbury Agricultural College in Australia. The systems thinking and practices which have guided, and been shaped by, the innovations are outlined, and the rationale and framework of the major programme are described. The subsequent emphasis has been placed on effective learning for agricultural managers and their technologist advisors. It is argued that problem solving and learning are essentially the same psychological processes and that taking a systems approach to investigating problem situations provides a more useful paradigm for learning about agriculture than reductionist, discipline-based approaches. Experiential learning and autonomy in learning are seen as consistent with this and are basic features of the programmes. A conceptual framework for problem solving that incorporates soft and hard systems and scientific reductionist methodologies has been developed. A contingency approach to situation improving is emerging as a less restrictive and more realistic alternative to a normative approach to problem solving.     

Peripheral giant cell granuloma in a cat

A gingival mass excised from a cat was determined to be a peripheral giant cell granuloma. Characteristic histologic features were large numbers of multinucleated giant cells intermixed with mononuclear mesenchymal cells in a loose fibrovascular stroma. The lesion recurred twice, indicating that these non-neoplastic growths may be locally invasive.