Evaluating the relationship of autumn buttercup (Ranunculus acriformis var. aestivalis) to some close congeners using random amplified polymorphic DNA

Autumn buttercup, an endangered endemic of wet, saline meadows in Garfield County, Utah, is treated differently in various taxonomic references now in use in the region. The taxon is currently listed as endangered by the United States Fish and Wildlife Service under the name Ranunculus acriformis var. aestivalis L. Benson. Others treat it as R. acris var. aestivalis (L. Benson) Welsh. In an attempt to resolve the taxonomical disagreements and to quantitatively describe the genetic uniqueness of this taxon, putative close relatives of the autumn buttercup, namely R. occidentalis (Nevada County, CA), R. acris (introduced from Europe and now growing wild in Rich and Cache counties, UT), R. acriformis var. montanensis (Lincoln County, WY), R. acriformis var. acriformis (Emery and Sanpete counties, UT), and R. acriformis var. aestivalis were collected and analyzed using random amplified polymorphic DNA (RAPD) genetic markers amplified from total cellular DNA extracts. Twenty-three decanucleotide primers of arbitrary sequence were used for DNA amplification; over 350 markers were generated. The genetic marker data were analyzed using similarity coefficients and parsimony. Based on the results of those analyses and on a review of ecological and morphological characteristics, we have elevated the autumn buttercup to species rank as Ranunculus aestivalis (Benson) Van Buren & Harper.     

Structure-function relationships of S-carboxymethyl methionine27 glucagon

Carboxymethylation of glucagon and subsequent purification of the hormone has provided a derivative modified by the addition of bulk to the methionine at position 27 without a net charge alteration in the side chain. Unreacted glucagon was removed after methylation of the methionine which provides a positively charged chromatographic handle. The derivative has a half-maximum concentration for binding of 5.3 nM and is a full agonist. These findings along with those provided by methylation of the methionine indicate that a positive charge rather than bulk on the methionine side chain disrupts the binding of hormone to its receptor. The S-carboxymethyl derivative lacks the concentration-dependent aggregation characteristic of glucagon at pH 10.2 as does the S-methyl derivative but increases its helical content in 30% 2-chloroethanol to the same extent as native and S-methyl hormone. Full activity of the S-carboxymethyl methionine27 glucagon does not favor the existence of the globular structure proposed by Korn and Ottensmeyer [(1983) J. Theor. Biol. 105, 403] as the binding species whereas multiple considerations do favor a flexible hormone with nucleation followed by conformational changes for complete binding and activation. Isotopic enrichment using labeled iodoacetate is feasible and can provide more definitive structural information.     

ANALYSIS OF RNA SYNTHESIZED BY AN ISOLATED RAT BRAIN SYNAPTOSOMAL FRACTION

Abstract— A synaptosomal fraction derived from rat brain, when incubated in an appropriate medium. incorporates [5-³H]uridine into RNA. On the basis of sedimentation analysis, RNA-DNA hybridization and metabolic inhibitor studies, mitochondrial RNA species appear to be the major, if not sole, RNA products synthesized by the isolated synaptosomal fraction. Electronmicroscope autoradiographic analysis showed that about 50% of the incorporation of [5-³H]uridine into RNA by this fraction occurs in the presynaptic endings. The capacity of mitochondrial RNA synthesis in isolated nerve endings declines as the age of the animal increases from 10 to 30 days, and by 60 days of age discrete mitochondrial RNA species are barely detectable.     

The American lung fluke, Paragonimus kellicotti, in a cat model

Twenty-four specific-pathogen-free domestic cats were infected orally with from 2 to 30 Paragonimus kellicotti metacercariae and followed for 2-61 wk. Following infection by metacercarial cysts dissected from crayfish, the lungs of the cats undergo changes of intense eosinophilic pneumonia, granulomatous pneumonitis, squamous epithelial-lined cyst formation of bronchogenic origin, and finally (late in infection) partial resolution of the host response. Bronchograms and mechanical probing illustrate the patency of cyst communication with bronchi. The modulation of the host response and adaptive changes in the host lung tissue are seen late in infection and have previously been unreported or underemphasized. These adaptive responses may account for the number of asymptomatic cases accidentally found in veterinary patients and the difficulty in prompt and proper diagnosis in human cases.     

A chemical approach to solving bridging phenomena in steroid radioimmunoassays

Steroid radioimmunoassays (RIA) employ antibodies raised against a carrier protein-steroid conjugate. Individual antibodies may recognize the steroid, the protein or the chemical bridge used to Join them together. Use of the same bridge In the tracer results in higher affinity binding of the tracer than the native ligand which in turn results in a loss of sensitivity and precision. We have greatly reduced bridge-binding In a RIA for androstenedione. Conjugates and radioiodinated labels were prepared with either an ester op ether chemical bridge. By using an antibody and the corresponding label with the heterologous bridge very sensitive assays were obtained.     

IS900-promoted stable integration of a foreign gene into mycobacteria

An artificial mycobacterial transposon was constructed by placing two copies of the insertion sequence IS900 flanking a kanamycin resistance gene into a non-(mycobacterial) replicating vector. Constructs were introduced into mycobacteria by electroporation and transposition events conferring kanamycin resistance were selected. Integration of IS900 into several genomic sites was analysed by Southern blotting and shown to involve both simple insertions and cointegrate formation, suggesting that IS900 can transpose by a replicative mechanism. Kanamycin resistance of IS900-integrated transformants was shown to be stable in the absence of selection.