Immunologic and nonimmunologic responsiveness in ragweed-sensitized dogs

The relationship between airway responsiveness to inhaled antigen and histamine, immunologic release of lung histamine, immunologic responsiveness of skin, and specific immunoglobulin E (IgE) antibodies were examined in 11 inbred allergic dogs immunized with extracts of ragweed and grass and 5 nonimmunized control dogs from the same colony. Airway responsiveness to antigen and histamine was characterized by the doses that increased the airflow resistance of the total respiratory system to twice the control values (ED200). Highly significant correlations were found between airway responsiveness and cutaneous responsiveness to antigen and other immunologic characteristics (e.g., IgE and histamine released from lung by inhaled antigen) in all dogs. In ragweed-sensitized dogs, there was an inverse correlation between immunologic responsiveness (reflected by the cutaneous response to antigen and histamine released from lung by inhaled antigen) and nonimmunologic responsiveness of airways (histamine ED200: r = 0.73, P less than 0.05 and r = 0.75, P less than 0.01, respectively). Antigen ED200 was also correlated with histamine release from lung after antigen inhalation (r = 0.74; P less than 0.01). We conclude that airway reactions to inhaled antigen in allergic dogs are dependent not only on immunologic factors but also on the degree of nonimmunologic airway responsiveness to histamine and that these factors are correlated inversely.     

Archaeal complex II: 'classical' and 'non-classical' succinate:quinone reductases with unusual features.

Reversible succinate dehydrogenase (SDH) activities have been ubiquitously detected in organisms from the three domains of life. They represent constituents either of respiratory complexes II in aerobes, or of fumarate dehydrogenase complexes in anaerobes. The present review gives a survey on archaeal succinate:quinone oxidoreductases (SQRs) analyzed so far. Though some of these could be studied in detail enzymologically and spectroscopically, the existence of others has been deduced only from published genome sequences. Interestingly, two groups of enzyme complexes can be distinguished in Archaea. One group resembles the properties of SDHs known from bacteria and mitochondria. The other represents a novel class with an unusual iron-sulfur cluster in subunit B and atypical sequence motifs in subunit C which may influence electron transport mechanisms and pathways. This novel class of SQRs is discussed in comparison to the so-called 'classical' complexes. A phylogenetic analysis is presented suggesting a co-evolution of the flavoprotein-binding subunit A and subunit B containing the three iron-sulfur clusters.     

Aminergic neuron systems of lobsters: morphology and electrophysiology of octopamine-containing neurosecretory cells

In the American lobster (Homarus americanus) the biogenic amines serotonin and octopamine appear to play important and opposite roles in the regulation of aggressive behavior, in the establishment and/or maintenance of dominant and subordinate behavioral states and in the modulation of the associated postural stances and escape responses. The octopamine-containing neurosecretory neurons in the thoracic regions of the lobster ventral nerve cord fall into two morphological subgroups, the root octopamine cells, a classical neurohemal group with release regions along second thoracic roots, and the claw octopamine cells, a group that selectively innervates the claws. Cells of both subgroups have additional sets of endings within neuropil regions of ganglia of the ventral nerve cord. Octopamine neurosecretory neurons generally are silent, but when spontaneously active or when activated, they show large overshooting action potentials with prominent after-hyperpolarizations. Autoinhibition after high-frequency firing, which is also seen in other crustacean neurosecretory cells, is readily apparent in these cells. The cells show no spontaneous synaptic activity, but appear to be excited by a unitary source. Stimulation of lateral or medial giant axons, which excite serotonergic cells yielded no response in octopaminergic neurosecretory cells and no evidence for direct interactions between pairs of octopamine neurons, or between the octopaminergic and the serotonergic sets of neurosecretory neurons was found.     

Ontogeny and homology of the skeletal elements that form the sucking disc of remoras (Teleostei,Echeneoidei, Echeneidae)

The sucking disc of the sharksuckers of the family Echeneidae is one of the most remarkable and most highly modified skeletal structures among vertebrates. We studied the development of the sucking disc based on a series of larval, juvenile, and adult echeneids ranging from 9.3 mm to 175 mm standard length. We revisited the question of the homology of the different skeletal parts that form the disc using an ontogenetic approach. We compared the initial stages of development of the disc with early developmental stages of the spinous dorsal fin in a representative of the morphologically basal percomorph Morone. We demonstrate that the “interneural rays” of echeneids are homologous with the proximal‐middle radials of Morone and other teleosts and that the “intercalary bones” of sharksuckers are homologous with the distal radials of Morone and other teleosts. The “intercalary bones” or distal radials develop a pair of large wing‐like lateral extensions in echeneids, not present in this form in any other teleost. Finally the “pectinated lamellae” are homologous with the fin spines of Morone and other acanthomorphs. The main part of each pectinated lamella is formed by bilateral extensions of the base of the fin spine just above its proximal tip, each of which develops a row of spinous projections, or spinules, along its posterior margin. The number of rows and the number of spinules increase with size, and they become autogenous from the body of the lamellae. We also provide a historical review of previous studies on the homology of the echeneid sucking disc and demonstrate that the most recent hypotheses, published in 2002, 2005 and 2006, are erroneous. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Use of a novel agarose gel-digesting enzyme for easy and rapid purification of PCR-amplified DNA for sequencing.

The use of a novel gel-digesting enzyme preparation provides an easy, rapid and convenient method to quantitatively recover PCR-amplified DNA from low melting point agarose gels. The PCR products purified using this method were readily sequenced and yielded good and unambiguous sequence data.     

A familial mutation in the testis-determining gene SRY shared by both sexes

A familial mutation in SRY, the gene coding for the testis-determining factor TDF, was identified in an XY female with gonadal dysgenesis, her father, her two brothers and her uncle. The mutation consists of a T to C transition in the region of the SRY gene coding for a protein motif known as the high mobility group (HMG) box, a protein domain known to confer DNA-binding specificity on the SRY protein. This point mutation results in the substitution, at amino acid position 109, of a serine residue for phenylalanine, a conserved aromatic residue in almost all HMG box motifs known. This F109S mutation was not found in 176 male controls. When recombinant wildtype SRY and SRY^F109S mutant protein were tested in vitro for binding to the target site AAC AAAG, no differences in DNA-binding activity were observed. These results imply that the F109S mutation either is a rare neutral sequence variant, or produces an SRY protein with slightly altered in vivo activity, the resulting sex phenotype depending on the genetic back-ground or environmental factors.This paper is dedicated by G. S. to Professor Ulrich Wolf on the occasion of his 60th birthday     

Plasma catecholamines: effects of footshock level and hormonal modulators of memory storage

Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in male Sprague-Dawley rats before and at several times after training injections of agents known to enhance or to impair later retention performance for a one-trial inhibitory (passive) avoidance task. Two days before testing, each animal was surgically prepared with a chronic tail artery catheter that allows for repeated blood sampling in unhandled rats. Exposure to a single, intense training footshock (3.0 mA, 2.0 sec duration) resulted in an immediate but transient increase in plasma levels of EPI and to a lesser extent NE. Plasma levels of both catecholamines did not differ between unshocked controls and animals that received a weak training footshock (0.6 mA, 0.5 sec duration). An injection of EPI at a dose that enhances retention performance (0.1 mg/kg, sc) resulted in increments in plasma EPI levels of 0.8-1.9 ng/ml from 5 to 40 min after injection. An injection of EPI (0.5 mg/kg, sc) at a dose that produces retrograde amnesia resulted in increments in plasma EPI ranging from 3.7 to 4.5 ng/ml during the 40 min after injection. Plasma NE levels were not significantly altered following an EPI injection. A single injection of adrenocorticotropin (ACTH, 0.3 or 3.0 IU per rat) did not alter the plasma catecholamine responses to training with a weak footshock. Similarly, the synthetic ACTH analog, Organon 2766 (125 or 250 mg/Kg) did not affect plasma catecholamines in untrained (unshocked) rats.These results demonstrate that significant increments in plasma levels of NE and EPI occur shortly after inhibitory avoidance training. Furthermore, an injection of EPI that enhances retention of an inhibitory avoidance task mimics the magnitude, though not the temporal characteristics, of the endogenous adrenal medullary response to a training footshock. Other hormonal treatments (ACTH and Organon 2766) which enhance memory storage do not affect plasma levels of NE and EPI.