Growth of Legionella pneumophila in association with blue-green algae (cyanobacteria).

Legionella pneumophila (Legionnaires disease bacterium) of serogroup 1 was isolated from an algal-bacterial mat community growing at 45 degrees C in a man-made thermal effluent. This isolate was grown in mineral salts medium at 45 degrees C in association with the blue-green alga (cyanobacterium) Fischerella sp. over a pH range of 6.9 to 7.6. L. pneumophila was apparently using algal extracellular products as its carbon and energy sources. These observations indicate that the temperature, pH, and nutritional requirements of L. pneumophila are not as stringent as those previously observed when cultured on complex media. This association between L. pneumophila and certain blue-green algae suggests an explanation for the apparent widespread distribution of the bacterium in nature.     

Increased recovery of salmonellae from environmental samples enriched with buffered peptone water.

The incidence and persistence of salmonellae in weather pools on the top of Stone Mountain were investigated with lactose and buffered peptone water used as pre-enrichment broths. A total of 162 samples were collected from 16 weather pools over a 3-month period. The use of buffered peptone water increased the recovery of salmonellae by approximately 25%. The combined use of direct enrichment in tetrathionate broth containing brilliant green dye and pre-enrichment in buffered peptone water followed by enrichment in tetrathionate broth made it possible to detect all 37 of the contaminated samples. All of the isolates were Salmonella bareilly, the only serotype recovered in a previous study. All but one of the isolations were made from moist or wet samples. S. bareilly was isolated from rabbit dung and litter collected near the weather pools, but attempts to trap rabbits for study were unsuccessful. Random samples taken along a side of the mountain yielded S. bareilly in weather pools within the upper third of the mountain; below this level, S. weslaco and S. memphis were recovered, but not S. bareilly.     

Both ankyrin and band 4.1 are required to restrict the rotational mobility of band 3 in the human erythrocyte membrane.

A population of band 3 proteins in the human erythrocyte membrane is known to have restricted rotational mobility due to interaction with cytoskeletal proteins. We have further investigated the cause of this restriction by measuring the effects on band 3 rotational mobility of rebinding ankyrin and band 4.1 to ghosts stripped of these proteins as well as spectrin and actin. Rebinding either ankyrin or 4.1 alone has no detectable effect on band 3 mobility. Rebinding both these proteins together does, however, reimpose a restriction on band 3 rotation. The effect on band 3 rotational mobility of rebinding ankyrin and 4.1 are similar irrespective of whether or not band 4.2 is removed from the membrane. We suggest that ankyrin and 4.1 together promote the formation of slowly rotating clusters of band 3.     

The Ecology of Seasonal Stress and the Origins of Agriculture in the Near East

The time, place, and reasons for the first domestication of cereals and legumes in the Near East can now be securely identified using combined evidence from paleoenvironmental studies, models of ecosystem dynamics, and regional archeology. The heartland of domestication was the Jordan Valley and surrounding region in the Southern Levant. Approximately 10,000 years ago, people began planting crops where the wild ancestral species had proliferated over two millenia. Impetus for domestication came from the synergistic effects of climatic change, anthropogenic environmental change, technological change, and social innovation. At the end of the Pleistocene, after a long period of climatic instability, a mediterranean climate more strongly seasonal than any today emerged with hyper-arid summers that selected for annual species of cereals and legumes. This occurred long after people had invented tools suitable for grinding hard seeds, but the new, lengthy dry season and consequent need to use stored foods encouraged sedentism among human groups who subsequently depleted their immediate environments of wild resources. These preconditions facilitated the development of agriculture. The scenario developed here is specific to the Near East, for such case studies of specific factors in independent regions of domestication are essential before we attempt to explain cases all over the world with reference to global causes.     

Ecological distribution of Legionella pneumophila.

Bacteria were concentrated 500-fold from 20-liter water samples collected from 67 different lakes and rivers in the United States. The data suggest that Legionella pneumophila is part of the natural aquatic environment and that the bacterium is capable of surviving extreme ranges of environmental conditions. The data further demonstrate the effectiveness of the direct fluorescent-antibody technique for detecting L. pneumophila in natural aquatic systems. Smears of the concentrated samples were screened microscopically for serogroups of L. pneumophila by the direct fluorescent-antibody technique. Virtually all of the 793 samples were found to be positive by this method. The 318 samples containing the largest numbers of positive bacteria which were morphologically consistent with L. pneumophila were injected into guinea pigs for attempted isolations. Isolates were obtained from habitats with a wide range of physical, chemical, and biological parameters. Samples collected monthly from a thermally altered lake and injected into guinea pigs demonstrated a seasonality of infection, with the highest frequency of infection occurring during the summer months.     

Protein-protein interactions of cytochrome oxidase in inner mitochondrial membranes. The effect of liposome fusion on protein rotational mobility

Rotational diffusion of cytochrome oxidase in the inner membrane of rat liver mitochondria was measured by detecting the decay of absorption anisotropy after photolysis of the heme a3.CO complex by a vertically polarized laser flash. As in previous experiments with beef heart mitochondria (Kawato, S., Sigel, E., Carafoli, E., and Cherry, R. J. (1980) J. Biol. Chem. 255, 5508-5510), co-existence of rotating cytochrome oxidase (mean rotational relaxation time, phi, of 700 to 1400 microseconds) and immobilized cytochrome oxidase (phi greater than 20 ms) was observed in mitochondria and mitoplasts. The effect of lipid/protein ratio by weight (L/P) on the relative proportions of mobile and immobile cytochrome oxidase was investigated following the fusion of soybean phospholipid vesicles with mitoplasts. The fusion procedure yielded four separate fractions upon sucrose density gradient centrifugation with L/P as follows: 0.3 in Pellet, 0.7 in Band 3, 1.5 in Band 2, and 3.0 in Band 1. The percentage of rotationally mobile cytochrome oxidase (phi = 700 to 1000 microseconds) in each of the different bands was found to be 16% in Pellet, 25% in Band 3, 47% in Band 2, and 76% in Band 1 at 37 degrees C. The dependence of the amount of mobile cytochrome oxidase on L/P indicates that the fraction of aggregated protein progressively decreases with decreasing concentration of proteins in the membrane. Thus, the large immobile fraction of cytochrome oxidase in mitochondrial inner membranes can be explained by nonspecific protein aggregation which is a consequence of the low L/P. The decrease in the mobile fraction in Pellet compared with mitoplasts was shown to be due to the pH 6.5 incubation used for fusion.     

Genetics of lipid deposition in the Japanese quail

Summary The research presented here was designed to investigate the mode of inheritance of fat and lean tissue deposition, and the relationship between them and body weight in Japanese quail. Heterotic effects were found for weight, size, and number of adipocytes in the abdominal fat depots, weight of the sartorial fat depot and percentage carcass fat with means for the hybrids being lower than those for the parental lines. General inferences concerning the importance of nonadditive genetic variation for lean and body weight were precluded due to inconsistencies observed among mating combinations. Thus, although heterosis and recombination effects were general for characteristics associated with fat deposition, the situation for body weight and lean was unique to the populations involved. It may be hypothesized that heterosis in the efficiency of feed utilization is reflected by the heterosis for fat deposition which explains why hybrids utilize feed better than their parental lines.     

Heparin enhances fibrinolysis in B16 mouse melanoma cells

The fibrinolytic activity of two tumorigenic B16 mouse melanoma lines was stimulated by exogenous hog mucosal or beef lung heparin. In contrast, the activity of two normal fibroblast lines was unaffected. The degradation of ¹²⁵l-fibrin was increased up to 3.6-fold by the addition of heparin. Chondroitin-4-sulfate or dextran sulfate did not change the fibrinolytic activity of three of the cell lines, but, at concentrations where enhancement by heparin was much reduced, the activity of one of the B16 melanoma lines was somewhat elevated. Antithrombin III did not alter the plasminogen activator activity of the B16 cell lines, but, in the presence of exogenous heparin, the enhancement of fibrinolysis was greatly reduced. The polymers were not cytotoxic during the assay period, and, had little affect on the plating efficiencies of the lines.     

Correlation between cell killing and massive second-round superinfection by members of some subgroups of avian leukosis virus.

Avian leukosis viruses of subgroups B, D, and F are cytopathic for chicken cells, whereas viruses of subgroups A, C, and E are not. The amounts of unintegrated linear viral DNA in cells at different times after infection with cytopathic or noncytopathic viruses were determined by hybridization and transfection assays. Shortly after infection, there is a transient accumulation of unintegrated linear viral DNA in cells infected with cytopathic avian leukosis viruses. By 10 days after infection, the majority of this unintegrated viral DNA is not present in the infected cells. The transient cytopathic effect seen in these infected cells also disappears by this time. Low amounts of unintegrated linear viral DNA persist in these cells. Cells infected with noncytopathic viruses do not show this transient accumulation of unintegrated viral DNA. Cells infected with cytopathic viruses and subsequently grown in the presence of neutralizing antibody do not show the transient accumulation of unintegrated viral DNA or cytopathic effects. These results demonstrate a correlation between envelope subgroup, transient accumulation of unintegrated linear viral DNA, and transient cell killing by avian leukosis viruses. The cell killing appears to be the result of massive second-round superinfection by the cytopathic avian leukosis viruses.     

Variations in population levels of citrus blackfly,Aleurocanthus woglumi [Hom: Aleyrodidae] and parasites during an eradication program in Florida

From November, 1976 until October, 1979 citrus blackfly,Aleurocanthus woglumi Ashby and its parasite populations were sampled monthly in urban areas of Broward County, Florida. During this period, the parasites,Amitus hesperidum Silvestri andProspaltella opulenta Silvestri became established and exerted control onA. woglumi populations. Parasite succession was noted in thatA. hesperidum was first abundant and later replaced in abundance byP. opulenta. The 2 parasite species continued to coexist and exert mortality on low pest populations in spite of chemical spraying used for eradication showing that integrated control ofA. woglumi is a definite possibility now that the pest is well established in Florida.

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Résumé De novembre 1976 à octobre 1979, on a échantillonné mensuellement dans les zones urbaines du Comté de Broward, Floride, les populations de la mouche noire des citrus,Aleurocanthus woglumi Ashby et de ses parasites. Pendant cette période les parasites,Amitus hesperidum Silvestri etProspaltella opulenta Silvestri se sont établis et ont limité les populations deA. woglumi. Une succession dans les parasites a été notée:A. hesperidum fut abondant d'abord et remplacé ensuite en fréquence parP. opulenta. Les 2 espèces ont continué à coexister et causent la mortalité des faibles populations du ravageur malgré les traitements chimiques utilisés pour l'éradication; ce qui montre la possibilité d'une lutte intégrée contreA. woglumi maintenant que ce ravageur est bien établi en Floride.