Electrophoretic evaluation of the taxonomic status of two species of sea anemone

Puerto Rican populations of two species of sea anemones (Bunodosoma cavernata and B. granulifera) which had previously been considered one were assayed electrophoretically for enzymes encoded by 12 loci. The two species shared no common allozymes at 6 of the 12 loci. Genetic distance and identity values based on these allozymes were computed for the Puerto Rican populations and for B. cavernata from Florida and B. granulifera from Panama. The Puerto Rican populations of both species had much higher genetic identities for their geographically distant conspecifics than for each other. These results indicate that the two species are reproductively isolated and should be considered as separate valid species. Average heterozygosities are presented which are the first published for coelenterate species.     

Separation and Identification of the Polar Lipids of Chromatium Strain D

The polar lipids of the autotrophically grown, obligately anaerobic, photosynthetic bacterium Chromatium strain D were separated by paper chromatography. Four major phospholipids were identified: lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. In addition, three glycolipids were observed and characterized, namely, monoglucosyldiglyceride, which is found in other biological systems, and (mannosyl, glucosyl)-diglyceride and (dimannosyl, glucosyl)-diglyceride, which heretofore have not been observed in nature.     

Decreased velocity of shortening in arterial smooth muscle from older (28- to 31-week-old) spontaneously hypertensive rats

An increased maximum velocity of shortening (Vmax) and increased shortening ability (delta Lmax) have been reported for caudal arterial smooth muscle from 16- to 18-week-old spontaneously hypertensive rats (SHR) compared with age-matched Wistar-Kyoto (WKY) control rats. It is known that hypertension results in hypertrophy of vascular smooth muscle. It is plausible that the faster Vmax of 16- to 18-week-old SHR arterial smooth muscle may slow down with age due to hypertrophy. The force-velocity (F-V) study done previously on caudal arterial strips from 16- to 18-week-old SHR and WKY rats was repeated on preparations from 28- to 31-week-old rats. An electromagnetic muscle lever was employed in recording force-velocity data. Analysis of these data revealed that the 28- to 31-week-old SHR (n = 7) mean F-V curve was not different from the 28- to 31-week-old WKY (n = 5) mean F-V curve (p greater than 0.05), and the shortening ability of 28- to 31-week-old SHR arterial muscle was significantly depressed compared with 28- to 31-week-old WKY arterial muscle (p less than 0.01). In conclusion, (i) although Vmax is faster in younger (16- to 18-week-old) SHR compared with age-matched WKY caudal arterial smooth muscle, SHR Vmax is not different from WKY Vmax in the older (28- to 31-week-old) rats. (ii) Shortening ability is greater in 16- to 18-week-old SHR caudal arterial strips compared with 16- to 18-week-old WKY strips, but is significantly depressed in 28- to 31-week-old SHR compared with 28- to 31-week-old WKY preparations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mechanics of caudal artery relaxation in control and hypertensive rats

Alterations of smooth muscle function can just as easily stem from mechanical alterations in its ability to relax as from alteration in contraction. Since a failure of arterial smooth muscle to relax may contribute to the development of hypertension, we felt it necessary to study the relaxation process in greater depth. The effect of load on the time course of relaxation of rat caudal artery smooth muscle was analyzed either by comparing afterloaded contractions against various loads or by imposing abrupt alterations in load. Unlike mammalian striated muscles in which relaxation was reported sensitive to loading conditions, relaxation in the smooth muscle of the rat caudal artery (n = 17) was found to be largely independent of loading conditions. This type of relaxation has been termed "inactivation-dependent" relaxation; it is typical of muscle tissue in which the calcium sequestering apparatus is poorly developed. Our results suggest that calcium resequestration, or some biochemical process downstream to it, is the rate-limiting step during relaxation in arterial smooth muscle and that this is not qualitatively different for hypertensive arterial smooth muscle. These analytic techniques were used in the study of relaxation of hypertensive vessels. Quantitative analysis of the relaxation curves showed that both isometric and isotonic relaxation time was prolonged in hypertensive arterial smooth muscle. Prolonged isotonic relaxation indicates that hypertensive arteries remain narrowed for prolonged periods compared with normotensive vessels. Such narrowed vessels may be a factor in the increased total peripheral resistance seen in genetic hypertension.     

Characterization of the Blood-Brain Barrier: Protein Composition of the Capillary Endothelial Cell Membrane

Microvessels were isolated from canine cerebral cortex, and the composition of the endothelial cell membrane was investigated. Endothelial cell membranes were separated from the surrounding basement membrane, solubilized, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis in 12% gels. Staining with Coomassie Blue revealed a characteristic banding pattern of at least 12 major proteins with apparent molecular weights between 14,000 and 250,000. When proteins from red blood cell ghosts were run simultaneously, no similarities were observed, except for proteins at apparent molecular weights of 43,000 (band 3) and 35,000 (band 4). These two proteins migrated exactly to the positions of the erythrocyte proteins actin and glyceraldehyde 3-phosphate dehydrogenase, respectively. Membrane glycoproteins in gels were also examined by the use of fluorescent lectins. Of the fluorescein isothiocyanate-conjugated (FITC) lectins tested, only FITC-concanavalin A had an affinity for any membrane components. Diazotized [125I]iodosulfanilic acid, a membrane-impermeable reagent, was used to label the internal (lumen) cell surface and the external (antilumen) cell surface. Autoradiography and determination of radioactivity levels in gel slices showed that several proteins were specifically labeled, and that major differences in radioactivity of proteins existed in internal and external labeling experiments. It is concluded that the protein composition of the luminal membrane is different from that of the antiluminal membrane.     

Electron microscopy of resorbing surfaces of dental hard tissues

Summary The resorbing surfaces of exfoliated or extracted human deciduous molar teeth were studied directly in the scanning electron microscope and indirectly by a single stage carbon replica technique for the transmission electron microscope. Some specimens of resorbing bone were also examined. Some of the material was examined after a simple washing process and some after removal of the organic matrix with hot 12 diamino ethane.The typical crossbanding of collagen could be seen on resorbing cement and dentine surfaces. This is taken as an indication that demineralisation is the first step in resorption. The very highly mineralised peritubular dentine remained proud of the resorbing surfaces thus indicating that its mineral component is in some way selectively protected.Enamel prism sheaths were also found to be selectively resistant to resorption and this is assumed to be related to the protection of the mineral component in these regions by their higher and/or different organic content. No prism sheaths were found next to the enamel-dentine junction and there was only a slight step down from the enamel to the dentine.Large remineralization crystals were found located at the borders between adjacent Howship's lacunae.The natural resorbing surfaces were compared with surfaces subjected to purely physical erosion by 5 keV argon ion beam bombardment (Boyde and Stewart, 1962).Our thanks are due to Mr. A.D.G. Stewart for permission to publish Fig. 5, which was prepared by him. The Cambridge Instrument Company Stereoscan scanning electron microscope was provided by the (U. K.) Science Research Council.     

A scanning electron microscope study of Craspedella sp. from the branchial chamber of redclaw crayfish,Cherax quadricarinatus,from Queensland,Australia

Epidermal topography was examined, including papillate ridges, grooves and ciliated sensory papillae of Craspedella sp. from the branchial chamber of redclaw crayfish, Cherax quadricarinatus, from Queensland, Australia. Rhandites were observed to discharge from ducts opening mainly in a small distal region of the ventral epidermis of the three central (of five) tentacles. These regions, devoid of ciliated sensory papillae, serve to adhere the anterior end of the worms during locomotion. Secretions from glands associated with the posterior attachment organ were observed to discharge from pores on the outside region of the ventral surface of the disc.A comparison of various scanning electron microscopy (SEM) fixation techniques showed that (1) hot fixatives at 90 °C provide most information on the largest number of epidermal structures and (2) different fixation regimes highlight different epidermal features.     

Physician-Patient Partnerships for Lifelong Health Monitoring

Progress against disease has created in some parts of the world a situation in which people can expect good health into the eighth decade of life and beyond. Ideally that involves a physician-patient partnership for health maintenance, wherein a patient actively develops a life-style that is conducive to health.The scientific base for health maintenance has been growing through epidemiologic demonstration of the relationship between health and such living habits as smoking, diet, exercise and the use of alcohol, and the significance of blood pressure and other precursors of health effects that can be determined by physical examination.Lifelong health monitoring of patients by physicians builds on this scientific base for health maintenance, which merely extends the presently well-established schema for monitoring health during pregnancy and infancy. Public readiness for a health-oriented, in addition to a disease-oriented, medical service is growing.