Effect of tranquilizers on the total acetylcholine content and acetylcholinesterase activity in the brain tissue of Arvicanthis niloticus

The effect of reserpine and meprobamate on the total acetylcholine content and acetylcholinesterase activity in the brain tissue of the kusu rat, Arvicanthis niloticus, was studied. The total acetylcholine content and acetylcholinesterase activity were determined 1 hr after i.p. injection of different doses of reserpine (0.25, 0.5 and 1 mg/ml/100 g body wt) and meprobamate (6.25, 12.5 and 25 mg/ml/100 g body wt). The effect of different time intervals (1, 10, 30 min, 1, 2.5, 5, 8, 12, 24 and 48 hr) on the total acetylcholine content and acetylcholinesterase activity was investigated after i.p. injection of 0.5 mg of reserpine and 12.5 mg of meprobamate/ml/100 g body wt. Both reserpine and meprobamate caused an increase in the total ACh content in the brain tissue of Arvicanthis niloticus which was suggested to be due to a decrease in the release of ACh, since both reserpine and meprobamate inhibited AChE activity after some tested periods. The effect of meprobamate was observed to be stronger than that of reserpine.     

Blidingia ramifera stat. nov. (Chlorophyta): a new marine alga for eastern North America

Blidingia minima var. ramifera is reported for the first time in eastern North America. It occurs in the Gulf of St. Lawrence, Nova Scotia and in Maine. In the estuary of the West and Rights Rivers (Antigonish Harbour, Nova Scotia) it is the most common intertidal alga and during its maximum growth period (June-August) covers 75–90% of the intertidal zone for several km of shoreline at the mouth of the Rights River. In culture, spore germination and early development were typical of the taxon as described from Europe. The taxon is raised to specific status as Blidingia ramifera stat. nov. Blidingia subsalsa is confirmed from New England based on observations of spore germination in plants from Maine and Connecticut.     

A new method for demonstrating argyrophil cells of the pancreas and intestines

A new method for demonstrating argyrophil cells of the pancreas and intestinal tract using a combined silver and reducing solution in sections of formaldehyde fixed tissue is described. Impregnating sections in a 60 C water bath, the procedure takes about 25 min. A microwave version that takes about 5 min is also given. Results are similar to those obtained with the Grimelius method for argyrophil cells.     

Recombinant human prorenin from CHO cells: Expression and purification

The gene for human preprorenin was obtained from total RNA prepared from primary human chorion cells. An expression vector was constructed containing an SV40 early promoter, a human preprorenin cDNA, bovine growth hormone poly-A addition signal, and a dihydrofolate reductase (dhfr) expression cassette. This vector was inserted into the DXB-11 Chinese hamster ovary (CHO) cell line. The recombinant protein was exported by CHO cells into the tissue culture media. At harvest the prorenin levels ranged from 1–5 mg/L. For prorenin isolation the cell culture supernatants were processed by filtration, concentration, dialysis, and batch extraction. Preparative-scale isolation of prorenin was accomplished using blue-dye chromatography and size-exclusion chromatography. The isolated prorenin yielded a single SDS-gel band with Mr 40,000. The proprotein was characterized with respect to N-terminal sequence and N-linked sugar composition. Trypsin-activated renin prepared from the proprotein was characterized with respect to N-terminal sequence andpH-activity profile. Enzyme activity was measured with a newly developed fluorogenic peptide substrate containing the P₆-P₃ sequence of human angiotensinogen.     

α1-Adrenergic Receptor-Mediated Downregulation of Angiotensin II Receptors in Neuronal Cultures

Previous evidence has suggested that brain catecholamine levels are important in the regulation of central angiotensin II receptors. In the present study, the effects of norepinephrine and 3,4-dihydroxyphenylethylamine (dopamine) on angiotensin II receptor regulation in neuronal cultures from rat hypothalamus and brainstem have been examined. Both catecholamines elicit significant decreases in [125I]angiotensin II-specific binding to neuronal cultures prepared from normotensive rats, effects that are dose dependent and that are maximal within 4-8 h of preincubation. Saturation and Scatchard analyses revealed that the norepinephrine-induced decrease in the binding is due to a decrease in the number of angiotensin II receptors in neuronal cultures, with little effect on the receptor affinity. Norepinephrine has no significant actions on [125I]angiotensin II binding in cultures prepared from spontaneously hypertensive rats. The downregulation of angiotensin II receptors by norepinephrine or dopamine is blocked by alpha 1-adrenergic and not by other adrenergic antagonists, a result suggesting that this effect is initiated at the cell surface involving alpha 1-adrenergic receptors. This is further supported by our data indicating a parallel downregulation of specific alpha 1-adrenergic receptors elicited by norepinephrine. In summary, these results show that norepinephrine and dopamine are able to alter the regulation of neuronal angiotensin II receptors by acting at alpha 1-adrenergic receptors, which is a novel finding.     

CYTOGENETIC STUDIES IN CLARKIA,SECTION PRIMIGENIA. IV. A CYTOLOGICAL SURVEY OF CLARKIA GRACILIS

Clarkia gracilis (2n = 28) is an allotetraploid which combines genomes from two subsections of section Primigenia. Natural populations consist of plants homozygous for a single chromosome arrangement, which may differ from the arrangements in other populations by one or more reciprocal translocations. One arrangement, the “standard,” was widespread. Cytological observations on plants derived from crosses between populations of C. gracilis, and on triploid plants derived from crosses with C. amoena subsp. huntiana, one of the parents of the tetraploid, were used to determine the end arrangements present. Ten arrangements were identified, and it was found that the standard amoena subgenome of C. gracilis is identical in end arrangement to the previously defined standard arrangement of the diploid C. amoena. Hence a race of C. amoena with this arrangement was involved in the hybridization which gave rise to C. gracilis. Evidence was found that other arrangements of C. amoena have probably been introduced into C. gracilis by subsequent introgressive hybridization. Cytological differences, coupled with differences in morphology, ecology, and distribution indicate that C. gracilis should be subdivided into four subspecies instead of the three presently recognized.     

Oligonucleotides with novel, cationic backbone substituents: aminoethylphosphonates.

Oligonucleotide (2-aminoethyl)phosphonates in which the backbone consisted of isomerically pure, alternating (2-aminoethyl)-phosphonate and phosphodiester linkages have been prepared and characterized. One of these single isomer oligonucleotides (Rp) formed a more stable duplex with DNA or RNA than its corresponding natural counterpart. Hybrid stability was more pH-dependent, but less salt-dependent than a natural duplex. The specificity of hybridization was examined by hybridization of an oligonucleotide containing one (2-aminoethyl)phosphonate to oligonucleotides possessing mismatches in the region opposite to the aminoethyl group. In contrast to oligonucleotides containing (aminomethyl)-phosphonate linkages, oligonucleotide (2-aminoethyl)phosphonates were completely stable to hydrolysis in aqueous solution. These oligonucleotides were resistant to nuclease activity but did not induce RNase H mediated cleavage of a complementary RNA strand. Incubation in a serum-containing medium resulted in minimal degradation over 24 hours. Studies of cell uptake by flow cytometry and confocal microscopy demonstrated temperature dependent uptake and intracellular localization. (2-Aminoethyl)phosphonates represent a novel approach to the introduction of positive charges into the backbone of oligonucleotides.     

Selfing versus outcrossing in the androdioecious clam shrimp,Eulimnadia texana (Crustacea,Conchostraca)

The clam shrimpEulimnadia texana is an androdioecious crustacean in which hermaphrodites may self fertilize or outcross with males but cannot outcross with other hermaphrodites. Outcrossing is maintained within most populations of this species despite the high genetic cost of sex, suggesting that compensating factors provide an advantage to outcrossing. We hypothesized that one such benefit would be the production of larger clutch sizes resulting from outcrossed matings. To test this prediction, we recorded the body sizes and clutch sizes of hermaphrodites which mated via selfing or bia outcrossing. Clutch sizes showed significant, almost exponential, increases as body size increased in both selfing and outcrossing hernmaphrodites. The rate of this increase was the same for both groups, and there was no significant difference in clutch size when body size was controlled for between the two fertilization types.     

Dirofilaria immitis: heartworm infection alters pulmonary artery endothelial cell behavior

Mupanomunda, Maria, Jeffrey F. Williams, Charles D. Mackenzie, and Lana Kaiser. Dirofilaria immitis:heartworm infection alters pulmonary artery endothelial cell behavior.J. Appl. Physiol. 82(2): 389-398, 1997.Thepathogenesis of filariasis has generally been attributed to eitherphysical presence of the adult parasites or the host's immune responseto the parasites. However, the spectrum of filariasis cannot beentirely explained by these causes, and other mechanisms must beoperative. It is now evident that factors released by filarialparasites likely contribute to the pathogenesis of filarial diseases.Adult heartworms (Dirofilaria immitis) reside in the rightheart and pulmonary artery, so the pulmonary artery should be exposedto the highest concentration of filarial factors. We tested thehypothesis that endothelium-dependent relaxation is altered in the invitro pulmonary artery from heartworm-infected dogs. Relaxationresponses to endothelium-dependent vasodilators (methacholine,bradykinin, substance P, and A-23187) and the non-endothelium-dependent vasodilator nitroglycerin and contractile responses were measured inrings of pulmonary artery from control and heartworm-infected dogs.Endothelium-dependent relaxation was assessed in the presence andabsence of inhibitors of nitric oxide synthase, cyclooxygenase, andguanylate cyclase. Responses to methacholine, substance P, and A-23187,but not to bradykinin, nitroglycerin, norepinephrine, or KCl, weredepressed in pulmonary artery from heartworm-infected dogs whencompared with control, suggesting that changes in endothelial cell andnot vascular smooth muscle behavior are involved in altered relaxation.The mechanism of endothelium-dependent relaxation in control pulmonaryartery appears to involve nitric oxide in the case of methacholine andboth nitric oxide and a cyclooxygenase product in the case ofbradykinin and A-23187. The mechanism of endothelium-dependentrelaxation in pulmonary artery from heartworm-infected dogs was notclearly elucidated. These data provide no evidence that heartworminfection globally influences either endothelial cell receptor functionor the vascular smooth muscle guanylate cyclase guanosine 3,5-cyclicmonophosphate system, making it likely that changes in intracellularsignaling are primarily responsible for the observed alteration ofendothelium-mediated relaxation. Alteration of endothelial cellfunction by filarial parasites may be an important component inthe pathology associated with filariasis.

     

Operation Crayweed: Ecological and sociocultural aspects of restoring Sydney’s underwater forests

Operation Crayweed focuses on the restoration of underwater forests that disappeared from the coastline of Sydney, Australia’s largest city, 40 years previously. We show how a combination of science, hands‐on restoration, community engagement and art has helped the project to reach its goals as well as raise awareness about the importance of underwater kelp forests that are experiencing global decline.