Studies of alveolar cell morphometry and mass clearance in the rat lung following inhalation of an enriched uranium dioxide aerosol

Summary Seventy-three rats were exposed to an aerosol of enriched uranium dioxide (UO₂), giving initial lung burdens of 26 to 447 µg at 6 days post-inhalation (PI). At 7 days PI 35 of these rats were further exposed to thermalised neutrons at a fluence of 1 x 10¹² neutrons CM^–2. There was no significant difference between the two groups in the clearance rate of the UO₂ particles from the lung, up to 590 days PI. The particles cleared relatively slowly over this period with a retention halftime in the lung of 160 to 176 days.Transmission electron microscope (TEM) studies of tissue from the alveolar region at 8 days PI showed that inhalation of UO₂ particles significantly increased the sizes of macrophage and type II cells, and the number of macrophage and type I cells. There was also a significant increase in the size of lysosomal granules within the macrophages after exposure to the UO₂ particles. The exposure to UO₂, neutrons and²³⁵U fission fragments had no significant effect on any of the cells above that observed in the animals exposed to UO₂ alone.Additional rats were exposed to the same neutron fluence without prior UO₂ inhalation. The alveolar cells of neutron-only exposed rats were, in size and number, typically no different from those in the completely unexposed control rats.     

Low nanogram detection of nucleotides using fast atom bombardment-mass spectrometry

The effect of trimethylsilyl (TMS) derivatization on detection limits of mononucleotides in fast atom bombardment-mass spectrometry (FAB-MS) was examined. FAB-MS methods were developed to optimize sensitivity using adenosine 5'-monophosphate as a model compound and then applied to reference standards of two clinically important nucleotides: tricyclic nucleoside-5'-monophosphate (TCNMP) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP). The detection limit for the TMS derivative of TCNMP was 2.5-5 ng/microliters and less than 2.5 ng/microliters for FdUMP as its TMS derivative. This is greater than two orders of magnitude more sensitive than the FAB-MS analysis of the corresponding free compounds. These low detection limits for the TMS derivatives were obtained using a narrow scan range, signal averaging, detection in the negative ion mode, and 3-nitrobenzyl alcohol as the matrix. Hydrolysis of one or more of the labile TMS groups did occur, with the extent of hydrolysis being greatest in the more protic matrices.     

The analysis of hypervariable DNA profiles: problems associated with the objective determination of the probability of a match

Summary A computerised system has been used to store DNA profiles from 3 hypervariable loci. This initial survey illustrates that band matching is only possible after analysis of the errors associated with electrophoretic systems. A number of databases have been constructed with the three probes investigated and two methods of frequency determination, binning and sliding window fitting, have been compared.     

AN AMPLIFICATION OF THE PHYLOGENETIC SPECIES CONCEPT

Abstract— The goal of a phylogenetic species concept is to reveal the smallest units that are analysable by cladistic methods and interpretable as the result of phylogenctic history. We define species as the smallest aggregation of populations (sexual) or lineagcs (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts). A character state is an inherited attribute distributed among all comparable individuals (semaphoronts) of the same historical population, clade, or terminal lineage. This definition of species is character-based and pattern oriented. Evolutionary explanations of phylogenetic species are consistent with contemporary explanations of processes of speciation, but require only the assumption of nested hierarchical pattern. We discuss the compatibility of the phylogenetic species concept with various biological needs for species and justify its use at the exclusion of alternative species concepts.     

Basement-membrane components associated with the extracellular matrix of the lymph node

Summary Lymph nodes contain an extensive array of extracellular matrix fibers frequently referred to as reticular fibers because of their reticular pattern and positive reaction with silver stains. These fibers are known to contain primarily type-III collagen. In the present study, frozen and plastic-embedded sections of mouse and human lymph nodes were subjected to immunostaining with a panel of monospecific antibodies directed against type-IV collagen, type-III collagen, laminin, entactin, and heparan sulfate proteoglycan. Immunofluorescent staining revealed that, in addition to being uniformly stained with antibodies to type-III collagen, these fibers also stained positively with antibodies to type-IV collagen and to other basement-membrane-specific components. Furthermore, the basement-membrane-specific antibodies stained the outer surface of individual fibers. These same type-III collagen-rich fibers were distinct from blood vascular basement membranes since they did not react with antibodies to factor VIII-related antigen, an endothelial-cell-specific marker. The role of these basement-membrane-specific components associated with the reticular fibers of lymphoid tissue is unknown. However, it is possible that the ligands promote attachment of reticular fibroblasts as well as macrophages and lymphocytes to the extracellular matrix fibers.     

The importance of Paracallisoma coecus and myctophid fishes to nesting fork-tailed and Leach's storm-petrels in the Queen Charlotte Islands, British Columbia

The diet of fork-tailed (Oceanodroma furcata) and Leach's storm-petrel(O.leucorhoa) was studied at Petrel Island, a small island northof Hippa Island in the Queen Charlotte Islands, British Columbiain 1983. The diet of the two storm-petrel species consistedmostly of the amphipod Paracallisoma coecus and fish. Most fisheswhich could be identified were myctophids, and may have beenacquired by storm-petrels at night. Fishes increased while P.coecusdeclined in importance as a food over the nestling season ofthe storm-petrels. The amount of oil also declined in the Leach'sstorm-petrel diet over the season. Since P.coecus contains muchoil, the seasonal decline of both P.coecus and oil was probablyassociated. Other less important foods were jellyfishes, copepods,isopods, euphausiids, shrimp, squid and octopus. Jellyfishes(Velella velella) only occurred in the diet of Leach's storm-petrels,which may relate to that storm-petrel feeding in open oceanwhere V. velella occurs most frequently. The most numerous copepodwas Neocalanus cristatus, which was only observed in the storm-petreldiet early on during the study period. An abyssal copepod, Bathycalanusbradyi, and the isopod Cirolana californiensis (tentativelyidentified, the latter only previously known from sea canyonsoff California) were surprising food items of storm-petrels.Most euphausiid prey consisted of Thysanoessa spinifera andEuphausia pacifica.     

Ac transposition in transgenic tomato plants

Summary As an initial step towards developing a transposon mutagenesis system in tomato, the maize transposable element Ac was transformed into tomato plants via Agrobacterium tumefaciens. Southern analysis of leaf tissue indicated that in nine out of eleven transgenic plants, Ac excised from the T-DNA and reintegrated into new chromosomal locations. The comparison of Ac banding pattern in different leaves of the same primary transformant provided evidnece for transposition during later stages of transgenic plant development. There was no evidence of Ds mobilization in tomato transformants.     

Effect of diisopropylfluorophosphate on muscarinic and gamma-aminobutyric acid receptors in visual cortex of cats.

Administration of diisopropylfluorophosphate (DFP), an organophosphorus (OP) compound, irreversibly inhibits acetylcholinesterase (AChE) and results in cholinergic hyperactivity. This study investigated muscarinic and gamma-aminobutyric acid (GABA) receptor changes in visual cortex of cats following an acute exposure to DFP. A single acute administration of DFP (4 mg/kg) decreased the number of muscarinic receptors at 2, 10, and 20 hours after treatment. GABA receptors were elevated at 2 and 10 hours but returned to within control levels at 20 hours. No significant alteration in muscarinic or GABA receptor affinity was noted. In all cases cortical AChE activity was inhibited 60-90%. These findings show a down regulation of muscarinic receptors after DFP associated with low AChE activity. GABA receptors also are altered, and may be part of a compensatory mechanism to counteract excess cholinergic stimulation.     

Salicyloylaspartate as an endogenous component in the leaves of Phaseolus vulgaris

An amide conjugate of o-methoxybenzoic acid and aspartic acid has been isolated from bean leaves. After extraction and methylation of plant material, this compound was isolated as two isomeric monoethyl monomethyl esters. The ethylation of the aspartyl carboxyl groups was shown to be a likely result of an extraction procedure utilising acidified ethanol, the methylation of the aromatic hydroxy of the methoxy group to be due to the derivatisation procedure. Studies with pentafluorobenzylation confirmed that the endogenous compound is o-hydroxybenzoylaspartate.