Parasympathetic innervation of canine tracheal smooth muscle

To investigate whether efferent parasympathetic fibers to the trachealsmooth muscle course through the pararecurrent nerve rather than therecurrent or the superior laryngeal nerve, we stimulated all threenerves in anesthetized dogs. We also recorded the pararecurrentnerve activity response to bronchoconstrictor stimuli and compared itwith pressure changes inside a saline-filled cuff of an endotrachealtube. Electrical stimulation (30 s, 100 Hz, 0.1 ms, 10 mA) increasedtracheal cuff pressure by 21.0 ± 3.2 and 1.3 ± 0.7 cmH₂O for the pararecurrent and the recurrent laryngealnerve, respectively. Stimulation of the superior laryngeal nerveincreased tracheal cuff pressure before, but not after, sectioning ofthe ramus anastomoticus, which connects it to the pararecurrent nerve.Intravenous administration of sodium cyanide increased pararecurrentnerve activity by 208 ± 51% and tracheal cuff pressure by14.4 ± 3.5 cmH₂O. Elevation of end-tidalPCO₂ to 50 Torr increased pararecurrent nerveactivity by 49 ± 19% and tracheal cuff pressure by 8.4 ± 3.6 cmH₂O. Further elevation to 60 Torr increasedpararecurrent nerve activity by 101 ± 33% and tracheal cuffpressure by 11.3 ± 2.9 cmH₂O. These results lead usto the conclusion that parasympathetic efferent fibers reach the smoothmuscle of the canine trachea via the pararecurrent nerve.

     

VARIATION IN ALCOHOL DEHYDROGENASE ACTIVITY AND FLOOD TOLERANCE IN WHITE CLOVER,TRIFOLIUM REPENS

Flooding results in induction of anaerobic metabolism in many higher plants. As an important component of anaerobic energy production, alcohol dehydrogenase (ADH) activity increases markedly in response to flooding in white clover, Trifolium repens. Significant inter-individual variation in flood-induced ADH activity exists in natural populations of T. repens. The genetic basis of this variation was analyzed by offspring-midparent regression of data from 75 greenhouse reared families; the estimated heritability of flood-induced ADH activity was 0.55 (±0.13). Genetic variation in flood-induced ADH activity has pronounced effects on physiological response and flood tolerance in this species. ADH activity is positively correlated with the rate of ethanol production, indicating that observed in vitro activity differences are manifested in in vivo physiological function. T. repens plants with higher ADH activities during flooding have greater flood tolerance (measured as growth rate when flooded/unflooded growth rate). Variation in ADH activity during flooding accounts for more than 79% of the variance in flood tolerance. On the basis of a limited field survey of populations occupying three sites differing in exposure to flooding conditions, individuals from site C, the most frequently flooded site, expressed significantly higher average ADH activity when flooded than individuals from site A, a site with no history of flooding. Since ADH activity levels are not correlated with electrophoretic mobility variation in T. repens, this work supports previous suggestions that regulatory variation in enzyme activity may play a central role in biochemical adaptations to environmental stress.     

FMRFamide-like Peptides in the Nervous and Endocrine Systems of the Digenean Helminth Echinostoma liei

FMRFamide-like immunoreactivity has been demonstrated in the digenean trematode Echinostoma liei. The functions of FMRFamide-like substances appear to be many and varied within the invertebrates, where they are involved in neurotransmission, cardiovascular regulation, muscular contraction and/or relaxation, and in co-ordination of growth and maturation. It is clearly indicated that FMRFamide-like substances function as neurotransmitter/neuromodulator in E. liei by the abundance of positively stained nerve fibres and perikarya seen throughout the CNS and PNS. A single endocrine-like cell also showing FMRFamide-like immunoreactivity is situated within the muscular cirrus pouch.     

Identification of HLA-B44 subtypes associated with extended MHC haplotypes

The HLA class I antigen B44 is found in each of two different extended major histocompatibility haplotypes (allele combinations of HLA-B, HLA-DR, and complement genes BF, C2, C4A, and C4B in linkage disequilibrium). Using isoelectric focusing, two variants of HLA-B44 were identified. The basic variant was found in all cell lines with the extended haplotype HLA-B44, DR7, FC31, and the acidic variant in all cell lines with the extended haplotype HLA-B44, DR4, SC30. The occurrence of each antigen variant with a unique extended haplotype explains previous observations concerning the nonrandom association of B44 variants with DR antigens.     

Detection of CaMV gene I and gene VI protein products in vivo using antisera raised to COOH-terminal β-galactosidase fusion proteins

Specific antisera were prepared to the inclusion body protein (gene VI product) and the gene I product of cauliflower mosaic virus (CaMV). Translational fusions between the lacZ gene and gene VI or gene I were constructed by cloning the relevant DNA fragments into the expression vectors pUR290, pUR291 or pUR292. Large amounts of fusion protein were synthesized when the inserted DNA fragment was in frame with the lacZ gene of the expression vector. These fusion proteins were used to raise specific antisera to gene VI and gene I proteins of CaMV. Antiserum to the gene VI product detected a range of proteins in crude extracts and in a subcellular fraction enriched for virus inclusion bodies. This range of proteins was further shown to be related to gene VI by Staphylococcus aureus V8 partial proteolysis. Antiserum to the gene I product detected viral specific proteins of 46, 42 and 38 K in preparations of CaMV replication complexes from infected plants but not in any other subcellular fraction.     

Insertion of the precursor of the light-harvesting chlorophylla/b-protein into the thylakoids requires the presence of a developmentally regulated stromal factor

The precursor of the major light-harvesting chlorophylla/b-proteins of photosystem II was synthesizedin vitro from a gene fromLemna gibba. When the labelled precursor was incubated with developing barley plastids, the precursor and the processed polypeptide were incorporated in the thylakoids in proportions that varied depending on the developmental stage of plastids. At early stages of development most of the precursor associated with the thylakoids could be removed by washing with 0.1 M NaOH, while in more mature plastids most of its was resistant to a NaOH wash. Insertion of the precursor into thylakoids required the presence of a stromal factor and Mg-ATP. The stromal factor is probably a protein. The insertion reaction has an optimal temperature of 25°C and a pH of 8. The appearance of the stromal factor and the thylakoid membrane's receptivity for the insertion of the precursor depended on the stage of plastid development. These observations are consistent with the hypothesis that the insertion of the precursor into the thylakoid prior to its proteolytic processing, is one of the steps involved in the assembly of the light-harvesting complex of photosystem II.     

Big Moose Basin: simulation of response to acidic deposition

The ILWAS model has been enhanced for application to multiple-lake hydrologic basins. This version of the model has been applied to the Big Moose basin, which includes Big Moose Lake and its tributary streams, lakes, and watersheds. The basin, as defined, includes an area of 96 km², with over 20 lakes and ponds, and 70 km of streams. Hydrologic and chemical calibrations have been made using data from seven sampling stations. When total atmospheric sulfur loading to the basin is halved, the model predicts, after four years of simulation, a decreasing sulfate concentration and to a lesser extent a rising alkalinity at Big Moose Lake outlet. At the end of four years, the results show an increase in pH of 0.1 to 0.5 pH units depending upon season.     

Soluble minerals in chemical evolution

The adsorption of 5-AMP and 5-CMP was studied in saturated solutions of several soluble mineral salts (NaCl, Na₂SO₄, MgCl₂·6H₂O, MgSO₄·7H₂O, CaCl₂·2H₂O, CaSO₄·2H₂O, SrCl₂·6H₂O, SrSO₄, and ZnSO₄·7H₂O) as a function of pH, ionic strength, and surface area of the solid salt. The adsorption shows a pH dependence; this can be correlated with the charge on the nucleotide molecule which is determined by the state of protonation of the N-1 nitrogen of 5-AMP or N-3 nitrogen of 5-CMP and the phosphate oxygens. The adsorption which results from the binding between the nucleotide molecule and the salt surface is proposed as being due to electrostatic forces. It was concluded that the adsorption was reversible in nature. The adsorption shows a strong dependence upon ionic strength and decreases with increasing ionic strength. Surface area is shown to be an important factor in evaluating and comparing the magnitude of adsorption of nucleotides onto various mineral salts. The implications of the results of the study are discussed in terms of the importance of soluble mineral salts as adsorption sites in the characterization of the adsorption reactions of an adsorbed template in biogeochemical cycles.