New ribosomal RNA gene locations in Gossypium hirsutum mapped by meiotic FISH

In this study we have mapped newly identified rDNA loci in Gossypium hirsutum. Four new minor 18S-26S rDNA loci, in addition to the sites previously identified, were mapped using fluorescence in situ hybridization (FISH) to heterozygous translocation (NT) quadrivalents (IVs). The newly detected 18S-26S rDNA loci were mapped to the right arms of chromosomes 8, 9, 15, 17, 19, 20, and 23 and the left arms of chromosomes 5, 11, 12, and 14. Using the rDNA loci as common reference points, we detected several erroneous arm assignments in the previously published map of NT breakpoints. The data are summarized in the form of an integrated map for all 17 known rDNA loci, relative to centromeres, telomeres, and NT breakpoints. This information will facilitate future locus-specific research on rRNA gene evolution and function. Received: 26 January 1998; in revised form: 28 May 1998 / Accepted: 12 February 1999     

Dielectrophoretic force: A comparison of theory and experiment

Because of the increasing use of dielectrophoresis in the dielectric characterization and sorting of living cells or their parts, it has become important to establish carefully the theoretical backgrounds for this effect. A comparison with experiment is made of the several versions of the theory for the dielectrophoretic force exerted by nonuniform electric fields upon a neutral object. The three fundamental approaches: the Maxwell-Strattonstress tensor, the effective dipole moment, and the ‘Helmholtz’ energy approach are presented along with the general solution given earlier by Pohl and Crane. These are found to agree closely with experiment in predicting the dielectrophoretic force upon various rods hung in specially shaped (isomotive) field distributions. On the other hand, an alternative formulation based upon a debatable assignment of fields local to the dipoles gave a good fit to the experimental data only for materials of very low permittivity, and fitted poorly in the case of highly polarizable materials. An improved derivation of the theory for stable dielectrophoretic levitation is also presented. This phenomenon is of particular interest in that it is based upon an apparent violation of the Earnshaw's theorem, and is useful in the study of the dielectric properties of individual living cells.     

Blood Levels and Management of Lithium Treatment

The limited value of plasma measurements in the management of treatment with lithium is discussed in the light of the mechanisms of its therapeutic actions and toxic effects.The plasma level of lithium usually rises twofold or threefold in the three to five hours after ingestion of each dose of delayed-release tablets and then gradually falls. The precise shape and height of the lithium curve depend on gastric emptying, which can be slowed with propantheline or speeded with metoclopramide. Depressed or demented patients may be irregular in taking their tablets and variable in food intake. Both the time of the blood test and this behaviour must be considered before changing the prescribed dose of lithium salt because of a laboratory result. A lithium tolerance curve may be a safer guide to treatment than single measures.Mild intermittent thirst is a common early side effect, and severe persistent thirst with polyuria is an uncommon later effect of daily intakes of at least 1,500 mg lithium carbonate. This diabetes insipidus is reversible, non-progressive, unrelated to plasma level, and distinct in attack from lithium-induced hypothyroidism, which may occur at low dosage but is also usually of late onset and reversible or treatable with thyroxine while lithium is continued. Obesity is another occasional effect of large doses. These side effects and the antimanic and prophylactic effects may have different mechanisms.     

On the multiplicity of the enzyme catalase in mammalian liver

Summary The literature on the complex multiplicity of mammlian catalase and the nature of the epigenetic modifications undergone by this enzyme has been reviewed, along with relevant comment on the subcellular localization and biological role of the enzyme.The epigenetic causations of multiplicity are established as being multifactorial and include oxidoreductive conversions of sulphydryl groups, the covalent attachment of carbohydrate, and partial proteolysis of the enzyme. Each of these epigenetic transformations may give rise to sets of multiple forms, and overlaps between these separate sets may give rise to extremely complex multiplicity patterns.It is concluded that any interpretation of catalase multiplicity which places emphasis on a single epigenetic causation is not compatible with the scope and variety of the available data on this enzyme. Instead, a holistic approach is urged — one giving due emphasis to the multiple causation of catalase multiplicity, and the interrelationships of these causations in the cellular situation. Rather than viewing the multiplicity of this enzyme as merely a series of interesting chemical modifications, emphasis is directed towards the fact that catalase heterogeneity povides a sensitive indication of the functional variations which occur within separate compartments of the subcellular structure, and hence becomes an essential element in any satisfactory understanding of the role of this enzyme in cellular processes.     

Roselle—a potentially important plant fiber

Not yet exploited in the Western Hemisphere, this jute-like African fiber possesses commercial possibilities and is obtained from a plant that furnishes also edible fleshy calyces and oil-containing seeds.     

Immunological changes in response to herpesvirus infection in abalone Haliotis laevigata and Haliotis rubra hybrids

Australian abalone production has been affected by outbreaks of abalone viral ganglioneuritis (AVG) caused by a herpesvirus (AbHV). In this study, we undertook experimental transmission trials by immersion to study the abalone immune response to infection with AbHV. Representative cellular and humoural immune parameters of abalone, including total haemocyte count (THC), superoxide anion (SO) and antiviral activity against herpes simplex virus type 1 (HSV-1), were examined in apparently healthy (sub-clinical) and moribund abalone after challenge. In the early infection, sub-clinical stage (days 1–3), THC was found to increase significantly in infected abalone. TaqMan qPCR confirmed 20.5% higher viral load in moribund abalone compared to apparently healthy abalone, indicating that the abundance of AbHV within abalone is linked to their clinical signs. At the clinical stage of infection, THC was significantly lower in moribund abalone, but increased in AbHV-exposed but apparently healthy abalone, in comparison to non-infected controls. SO was reduced in all abalone that were PCR-positive for AbHV. THC and SO level were found to be negatively correlated with the presence of AbHV in abalone, but no effect of AbVH exposure was observed on the haemolymph antiviral activity. These results suggest that abalone mount an initial cellular immune response to AbHV infection, but this response cannot be sustained under high viral loads, leading to mortality.     

Genbank accession #: AJ237597

Plant Molecular Biology -