Plant growth regulatory metabolites from novel actinomycetes

Metabolites from 796 isolates of aerobic actinomycetes were screened for plant growth regulatory properties using an algal bioassay. These included 266 isolates ofStreptomyces, 28 unidentified actinomycetes, and 502 isolates of novel actinomycetes represented by 18 genera. Algal growth inhibition of 30% was observed with 60 isolates, 37 of which belonged to the genusStreptomyces. Among other inhibitors were 8 isolates ofActinomadura, 6 ofActinoplanes, 2 each of the generaThermomonospora, Streptoverticillium, andPromicromonospora, and 3 unidentified. Metabolites from 70 isolates promoted algal growth by 20%. These included 13 isolates ofMicromonospora, 11 ofStreptomyces, 6 ofNocardia, 5 ofActinomadura, and 4 each ofRhodococcus andThermomonospora. Sixteen unidentified isolates; 3 isolates ofPromicromonospora; 2 isolates each ofActinoplanes, Streptosporangium, andOerskovia; and 1 of Thermoactinomyces peptonophilus-like organism andSaccharomonospora viridis also promoted the algal growth by 20%. The plant growth inhibitory properties of 9 actinomycetes and the growth promoting properties of 6 were demonstrable during the secondary screening on higher plants using chemicals extracted from the culture broth. The metabolites fromMicromonospora, Nocardia, Rhodococcus, Streptosporangium, andOerskovia isolates were associated with plant growth promotion only; those fromStreptomyces were most frequently involved with the growth inhibition.This is Michigan Agriculture Experiment Station Journal Article No. 12191.     

Relationship between fumonisin contamination of feed and mystery swine disease

Fumonisin is a recently identified mycotoxin that has been shown to be the cause of pulmonary edema disease in swine and leukoencephalomalacia in horses. Mystery Swine Disease (MSD), is an economically devastating disease complex of unknown etiology that has been reported to have occurred in several swine producing states since 1988. To determine the relationship between MSD and fumonisin, a case-control study was carried out in Illinois in mid-1990. Feed samples collected from 12 case and 9 control farms were analyzed for fumonisin. Sera from swine on all farms was screened for titers against encephalomyocarditis (EMC) virus and concentrations of alpha-1 acid glycoprotein (an acute phase reactive protein). Fumonisin concentrations 20 ppm were found on 1 control farm (1/9) and 8 case farms (8/12). Titers against EMC virus ( 116) were found on 5 control farms (5/9) and on 6 case farms (6/12). Farms with 20 ppm fumonisin in the feed were at significantly increased risk (OR= 11.2, Fisher's exact test p=0.037) for MSD. Furthermore, the ² test for trend was significant (p= 0.017), meaning that as the level of fumonisin in the feed increased, the risk of MSD also increased. The presence of EMC virus titers in the sow herd was not a significant risk for MSD (OR =1.25, Fisher's exact test p=0.75). Alpha-1 acid glycoprotein concentrations obtained from 2-week old nursing pigs differed significantly (p=0.0005) between MSD case and control herds.     

Comparison of 1980 Lake Huron,Georgian Bay - North Channel surveillance data with historical data

A statistical regionalization procedure was used to delineate significantly (p 0.10) different areas, for a variety of surveillance parameters measured in 1980 in Lake Huron and Georgian Bay-North Channel. The analyses performed were compared with similar analyses done on 1971 (Lake Huron) and 1974 (Georgian Bay-North Channel) data. The regions produced from the 1980 analyses compared favourably with the 1971 and 1974 analyses. Significant (p 0.01) increases in NO₃NO₂-N and RSiO₂ were observed for Lake Huron between the 1971 and 1980 data sets. Significant (p 0.01) increases in NO₃NO₂-N and significant (p 0.01) decreases in TP and chlorophyll a were observed for Georgian Bay-North Channel between the 1974 and 1980 data sets.     

Ecological observations on Heterotrophic,methane oxidizing and sulfate reducing bacteria in Pond

Numbers of heterotrophic, methane oxidizing and sulfate reducing bacteria were counted in Lake Vechten. A dynamic distribution pattern was found in the stratified lake. A maximum of heterotrophs (numbers of 10⁹ bact./l) occured in the deepest part of the lake in spring and in the metalimnion during summer-stratification. These bacteria use nearly all available oxygen in the hypolimnion. It was found that the concentration of available organic material and the oxygen tension caused the numbers of heterotrophs in the metalimnion to be high.The maximal numbers of methane oxidizers (numbers of 5.10⁵ bact./l) were found at a depth of maximal methane concentration: the de-oxygenated hypolimnion. Preliminary evidence indicated that these organisms were facultative methane oxidizers and must be regarded as micro-aerophyllics. By oxidizing methane they removed the residual oxygen under the metalimnion.The sulfate reducing bacteria could be observed in the hypolimnion only. Decreased SO _inf4 ^sup–2 concentration and increased numbers, of bacterai were found in the bottom water. An association between the methane oxidizers and the sulfate reducers could be deduced. It was assumed that favourable redox requirements for obligate anaerobic sulfate reducers were the results of the activities of the methane oxidizing bacteria.The dynamic distribution equilibrium of the investigated groups of bacteria was disturbed by the autumn turn-over. The heterotrophic and methane oxidizing bacteria decreased in number at that period and were equally distributed, no sulfate reducers could be detected in the free water of Lake Vechten.     

Correlation between hydrophobicity and resistance to nonoxynol-9 and vancomycin for urogenital isolates of lactobacilli

Seven clinical isolates of lactobacilli were found to be relatively hydrophobic with a mean water-contact angle of 66 +/- 15 degrees, and to be susceptible to 1% nonoxynol-9 and vancomycin. However, seven other strains were relatively hydrophilic with a mean water-contact angle of 32 +/- 13 degrees, and found to be resistant to 25% nonoxynol-9 and vancomycin. Thus, the surface properties of lactobacilli that influence susceptibility to antimicrobial agents may involve surface hydrophobicity. Possibly the penetration barrier posed by the cell surface towards these two nonionic antimicrobials is lower for hydrophobic cells than for hydrophilic cells.     

Human branched-chain L-amino acid aminotransferase: Activity and subcellular localization in cultured skin fibroblasts

Summary Assay conditions for measurement of human skin fibroblast branched-chain L-amino acid aminotransferase activity were established and applied to studies on subcellular distribution and kinetic properties of the enzyme. Digitonin fractionation of cultured cells revealed that the aminotransferase activity was mainly (at least about 95%) associated with mitochondrial citrate synthase activity. As tested with L-leucine, activity of the enzyme against amino group acceptors (forward reaction) was in the order 2-oxoglutarate branched-chain > straight-chain 2-oxo acids (C₃-C₈). With 4-methyl-2-oxopentanoate, activity against amino group donors (reverse reaction) was in the order L-glutamate branched-chain > straight-chain (C₂-C₆) and other L-amino acids. The data suggest that, in human fibroblasts, isoenzyme type I resides within the mitochondrial space. Possible implications for the metabolism of branched-chain compounds are discussed.     

Water column and sediment nitrogen and phosphorus distribution patterns in the Florida Keys,USA

Measurements of the distribution patterns of nutrients (ammonium, nitrate, orthophosphate, total N and total P) and chlorophyll concentrations were conducted under an interdisciplinary program known as SEAKEYS, initiated because of concern that anthropogenic nutrients may be impacting Florida coral reefs. Samples were collected along transects that extended from passes or canals to 0.5 km offshore of the outermost reefs. Seven of the transects were either in the Biscayne National Park (BNP) and Key Largo (upper keys) or Seven Mile Bridge/Looe Key (upper part of lower keys) areas, which have the best present-day reef development; the two in the middle keys off Long Key were in an area of minimal reef development where passes allow estuarine Florida Bay water to flow onto the Florida reef platform. Off the upper keys, water column concentrations of N and chl a were elevated near marinas and canals (1 M NO₃, 1 g/l chl a), but returned to oligotrophic levels (e.g., chl a 0.25 g/l; NO₃ 0.25 M; NH₄ 0.10 M) within 0.5 km of shore. Phosphorus concentrations, however, were often higher offshore 0.2 M PO₄). Sediment interstitial nutrient concentrations decreased from inshore to the offshore reef areas (e.g., 100 M NH₄ inshore to 50 M NH₄ offshore) and were comparable to those of some presumably pristine coastal and reef carbonate sediments. Sediment bulk N was higher nearshore and decreased steeply offshore ( 60 g-at N/gm sediment to 20 g-at N/gm sediment, respectively); bulk P concentrations ( 6 g- at P/gm sediment) varied little or exhibited the reverse pattern. Sediment N:P ratios were consistently lower offshore (1–10 vs. 20–40 nearshore). Higher offshore P concentrations are attributed to periodic upwelling along the shelf edge. In the middle keys water column nutrients and chl a concentrations were both higher than those in the upper keys, and there was less of an inshore-offshore decrease than that noted in the upper keys. Sediment nutrients were higher also, and nearshore and offshore areas did not differ. Water column and sediment nutrient concentrations and distribution patterns in the upper part of the lower keys were most similar to those measured in the upper keys. Overall, the present data do not support the contention that reef areas in the upper keys are accumulating elevated loads of land-derived nutrients via surface water flow, but does document moderately elevated nutrient and chl a levels in many developed nearshore areas. Most of the anthropogenic and natural nutrients entering the coastal waters from shore appear to be taken up by near shore algal and seagrass communities before they reach patch reef areas. Further work is needed to determine whether nutrient-enriched ground waters reach the reefs, however these would be expected to cause an enrichment of reef sediments, which was not observed.     

Extracellular ATP binding proteins as potential receptors in mucociliary epithelium: Characterization using [32P]3′-O-(4-benzoyl)benzoyl ATP,a photoaffinity label

3-O-(4-benzoyl)benzoyl ATP (BzATP) was used as a photoaffinity analog of ATP to label potential ATP receptors in ciliated cells. Like ATP, without photoactivation, BzATP stimulated the ciliary beat frequency in tissue culture up to threefold. Irradiation of intact cells in the presence of [-³²P]BzATP followed by SDS-PAGE and autoradiography revealed two labeled proteins with molecular masses of 46 and 96 kDa (p46 and p96). Photolabeling of both proteins was susceptible to digestion with trypsin, implying that the labeled proteins are at least partially exposed on the extracellular surface of the plasma membrane. The dependence of ³²P incorporation in both proteins on [-³²P]BzATP concentration was similar. Labeling of p46 but not p96 required Ca²⁺ or Mg²⁺. Various nucleotides stimulated the ciliary frequency, and inhibited the photolabeling of p46 and p96. The rank order of apparent affinity for p46 is: ATP ÃDP>GTPS>ADP S, UTP, 2MeSATP, AMP-PNP >AMP-PCP>AMP>adenosine; for p96 it is: ADPADP S ATP AMP-PCP, AMP-PNP>GTPS AMP>2MeSATP, UTP, adenosine. The rank of stimulation of ciliary beat frequency is: ADPS, UTP 2MeSATP, GTPS, AMP-PNP, ATPADP>AMPPCP>adenosine>AMP. These results suggest the involvement of p46 in the stimulatory effect of extracellular ATP on the ciliary beat, as a P₂ purinoceptor. On the other hand, p96 may represent a P₂ purinoceptor or an ectonucleotidase.This work was supported by grants (to Z.P. and to V.S-B.) from the Fund for Basic Research administered by the Israel Academy of Science and Humanities.     

Association of CTG repeats and the 1-kbAlu insertion/deletion polymorphism at the myotonin protein kinase gene in the Japanese population suggests a common Eurasian origin of the myotonic dystrophy mutation

We have studied linkage disequilibrium between CTG repeats and anAlu insertion/deletion polymorphism at the myotonin protein kinase gene (DMPK) in 102 Japanese families, of which 93 were affected with myotonic dystrophy (DM). All of the affected chromosomes are in complete linkage disequilibrium with theAlu insertion allele. Among the normal chromosomes, alleles of CTG repeats 5 and 17 are exclusively associated with the insertion allele. On the other hand, intermediate alleles of 11-6 repeats show a significantly greater association with the deletion allele. A strikingly similar pattern of linkage disequilibrium observed in European populations suggests a common origin of the DM mutation in the Japanese and European populations.     

Diagnosis of disseminated candidiasis in hospitalized patients using the Cand-Tec latex agglutination assay

A total of 1,303 sera from 202 patients at risk for disseminated candidiasis were analyzed for the presence of Candida antigen using a commercially available latex agglutination test (Cand-Tec). Twentythree patients had disseminated candidiasis documented by positive blood cultures, deep biopsy culture and histopathology or autopsy. Six patients had transient candidemia, 15 patients had candiduria, 62 patients were not colonized yet treated empirically with amphotericin B, and 46 patients were not colonized and not treated with amphotericin B. The sensitivity and specificity of the Candida antigen test for the diagnosis of disseminated candidiasis was 87% and 36% (threshold titer of 12), 70% and 60% (14), and 30% and 85% (18), respectively. In contrast to previous studies we were unable to demonstrate a prognostic role for the Candida antigen test in patients with documented disseminated candidiasis. The lack of sensitivity and specificity of the Cand-Tec Candida antigen test precludes its use in the diagnosis of disseminated candidiasis.     

Quantitative analysis of the Hopf bifurcation in the Goodwin n-dimensional metabolic control system

We study, from a quantitative point of view, the Hopf bifurcation in an ODE model of feedback control type introduced by Goodwin (1963) to describe the dynamics of end-product inhibition of gene activity. We formally prove that the exchange of linear stability of the positive equilibrium in the n-dimensional Goodwin system with equal reaction constants coexists with a Hopf bifurcation of nontrivial periodic solutions emanating from this equilibrium, without any further restriction on the dimension n 3 or on the Hill coefficient . The direction of the bifurcation, and the stability and the period of the bifurcating orbits are estimated by means of the algorithm proposed by Hassard et al. (1981).Supported by MURST 40/60%     

Coprecipitation of nonoxynol-9 with polyvinylpyrrolidone to decrease vaginal irritation potential while maintaining spermicidal potency

The aim of this study was to test the hypothesis that polyvinylpyrrolidone (PVP) would increase the critical micelle concentration (CMC) of nonoxynol-9 (N-9), providing a reduction in its irritation potential, while maintaining essential spermicidal activity. Solid coprecipitates of N-9 with PVP were manufactured with the use of a modified lyophilization process. The irritation potential of N-9 was estimated by an in vitro assay, monitoring the extent of hemolysis of red blood cells. CMCs of N-9 were measured in the presence of various concentrations of PVP. A modified Sander-Cramer assay was implemented to measure the spermicidal activity of N-9 and the N-9/PVP coprecipitates. With the use of the lyophilization process and more suitable solvents, solid coprecipitates of N-9/PVP were manufactured with no residual organic solvents. The irritation potential of N-9 was reduced when in the presence of PVP-50% hemolysis values increased from 0.054mM to more than 0.2mM. N-9 CMC values increased in the presence of PVP from 0.085mM (0% PVP) to 0.110mM (3.5% PVP) and 0.166mM (10% PVP). However, spermicidal activities ranged from 0.213mM to 0.238mM, N-9 remaining steady regardless of the amount of PVP. By use of N-9/PVP coprecipitates, the self-association properties and irritation potentials of N-9 were altered. This result suggests a process to produce a spermicidal product that reduces the detrimental implications to the vaginal epithelium while maintaining the essential spermicidal activity.     

Light-dependent phagotrophy in the freshwater mixotrophic chrysophyte Dinobryon cylindricum

The mixotrophic (bacterivorous), freshwater chrysophyte Dinobryon cylindricum was cultured under a variety of light regimes and in bacterized and axenic cultures to investigate the role of phototrophy and phagotrophy for the growth of this alga. D. cylindricum was found to be an obligate phototroph. The alga was unable to survive in continuous darkness even when cultures were supplemented with high concentrations of bacteria, and bacterivory ceased in cultures placed in the dark for a period longer than one day. Axenic growth of the alga was poor even in an optimal light regime. Live bacteria were required for sustained, vigorous growth of the alga in the light. Carbon (C), nitrogen (N), and phosphorus (P) budgets determined for the alga during growth in bacterized cultures indicated that bacterial biomass ingested by the alga may have contributed up to 25% of the organic carbon budget of the alga. Photosynthesis was the source of most (75%) of the organic carbon of the alga. D. cylindricum populations survived but did not grow when cultured in a continuous low light intensity (30 E m^–2 sec^–1), or in a light intensity of 150 E m^–2 sec^–1 for only two hours each day. Net efficiency of incorporation of bacterial C, N, and P into algal biomass under these two conditions was zero (i.e., no net algal population growth). We conclude that the primary function of bacterivorous behavior in D. cylindricum may be to provide essential growth factor(s) or major nutrients for photosynthetic growth, or to allow for the survival of individuals during periods of very low light intensity or short photoperiod. Offprint requests to: David A. Caron     

Tolerance of pesticides and antibiotic resistance in bacteria isolated from wastewater-irrigated soil

A total of 64 bacterial isolates (40 Pseudomonas spp., 12 Azotobacter and 12 Rhizobium spp.) were characterized on the basis of morphological, cultural and biochemical characteristics. All the isolates were tested for their tolerance to the pesticides endosulfan, carbofuran, and malathion. 12.5% of the Pseudomonas isolates from soil tolerated concentrations of 1600 g malathion ml whereas 7.5% of isolates tolerated the same concentration of carbofuran. However, Pseudomonas isolates demonstrated a tolerance limit to endosulfan at a concentration of 800 g/ml. Asymbiotic N₂-fixers (Azotobacter) and symbiotic N₂-fixers (Rhizobium spp.) were also able to tolerate concentrations of pesticides up to 1600 g/ml. All the isolates were further tested for their antibiotic susceptibility against seven different antibiotics, nalidixic acid, cloxacillin, chloramphenicol, tetracycline, amoxycillin, methicillin, doxycycline. 100% of the Pseudomonas isolates were resistant to cloxacillin and 57.5% were resistant to methicillin. 7.5% of the isolates exhibited multiple resistance to five different antibiotics in three different combinations whereas 25% of the isolates showed multiple resistance to four different antibiotics in seven different combinations. Some of the resistant isolates were also screened for plasmid DNA and found to harbour a single plasmid.     

Availability of suitable phytoplanktonic food for zooplankton in an ice-covered lake

Edible phytoplankters were found throughout the winter in a shallow ice-covered lake in Pennsylvania, U.S.A., in conjunction with a diverse population of zooplankton. Environmental conditions during the winter seemed to eliminate large and non-motile types of algae in favor of the smaller motile forms which may be the best foods for zooplankters. The phytoplankton were classified for study both by systematic position and by size group. The total volume of phytoplankton comprising the group Chrysophyta and algae 80 µ declined rapidly during the period of ice-cover, while algae 15 µ and Chlorophyta maintained more stable volumes. During the latter weeks of ice-cover phytoplankton densities were low (50–200/ml), and bacteria, detritus, or µ-algae (2 µ) not detected by the counting methods used, may have been important foods for the zooplankters. The lack of suitable phytoplanktonic foods may have contributed to the decline of calonoid copepods during the late winter.Based on a thesis submitted to the Department of Biology, East Stroudsburg State College, as a partial requirement for the degree of M.S. in Biology.     

Growth characteristics of the heterotrophic bacterial population of water and bottom sediments in tanks under different trophic conditions

Treatment of single and double doses of fertilizers had a definite response on the bacterial population of water and bottom sediments in tanks after 7 days (F_2,21 3.61; P < 0.05), but did not cause any significant change after day 32 (F_2,18 1.67; P > 0.05). Although the generation time of water bacteria did not vary much in these treatments of trophic gradients (P > 0.05), there was always a distinct variation (P < 0.01) in the generation time of the bacterial population of bottom sediments. The population size of water bacteria was shown to maintain an inverse relationship with the diurnal variation of temperature (P < 0.05) and dissolved oxygen (P < 0.05) of the water. The changes in the size of the bacterial population of water were positively correlated with the variations of hardness (P < 0.05), chloride (P < 0.05) and ammonia nitrogen (P < 0.05) of water. Although the relationships between the heterotrophic bacterial population and the inorganic phosphate of water was not convincing (P > 0.05), an inverse relationship was established between the bacterial community of bottom sediments and the phosphate content of the water (P < 0.01).     

A branching process model for the evolution of transposable elements

A discrete-time multitype branching process model is presented for the evolution of transposable elements in haploid populations. An individual is classified as type i if it possesses i copies of the TE, i0. The general model incorporates copy-dependent selection and transposition, and recursion relations are derived for the distribution of the number of individuals of the various types. The asymptotic relative proportions of individuals of the different types is studied in the neutral case. The behavior of this equilibrium distribution is examined for various patterns of regulated transposition and deletion.     

Estimating the age of Antarctic larval fish from otolith microstructure using light and electron microscopy

Larval fish of Antarctica have very narrow rings on their otoliths (<1 m) that may not be resolved with light microscopy. In this study, age data from the otoliths of larval Nototheniidae (Gobionotothen gibberifrons and Lepidonotothen larseni), determined using light and scanning electron microscopy, are compared. Rings 0.4 m wide were observed on otoliths viewed under electron microscopy; however, light microscopy could only resolve rings 0.5 m wide. Scanning electron microscopy is more time consuming and costly than light microscopy but has greater resolving power and is recommended to validate ring counts made using light microscopy in otolith studies with Antarctic larval fish.     

Global stability and oscillations in classical Lotka-Volterra loops

The paper considers the classical Volterra system of n ( 3) species in predator-prey relation forming a loop, and derives some global properties of its solutions. Sufficient conditions for global asymptotic stability in terms of parameters are obtained, and also the region of global boundedness in the parameter space is indicated. Lastly a three species system is discussed in detail in relation to its global stability, unboundedness of solutions, existence of periodic and non-periodic oscillations.Work performed under the auspices of G.N.F.M., C.N.R. (Italy) and within the activity of the group Evolution Equations and Applications, M.P.I., (Italy)     

Plasmid incidence in bacteria from agricultural and industrial soils

Heavy metal contents of agricultural and industrial soils were determined by atomic absorption spectrophotometry. The analysis of the samples collected from two different locations revealed significantly high levels of Fe, Zn, Cu, Cr and Ni. Certain microbiological parameters (total aerobic heterotrophs, asymbiotic N₂-fixers, total Actinomycetes and fungi) were also monitored from these soils. A total of 70 bacterial isolates from agricultural and industrial soils were examined for plasmid DNA content and resistance to the antibiotics amoxycillin, cloxacillin, chloramphenicol, doxycycline methicillin, nalidixic acid, and tetracycline. Minimum inhibitory concentrations (MICs) of Cu, Cr, Pb, Cd, Hg, Zn, and Ni for each isolate were also determined. Resistance was most frequent to methicillin (48.5%), cloxacillin (45.7%), and nalidixic acid (40%) for all isolates of bacteria. The highest MICs observed were 100 g/ml for mercury, 800 g/ml for Ni and 1600 g/ml for other metals. The incidences of metal resistance and MICs of metals for bacteria from industrial soil were significantly different to those of agricultural soil. On a percentage basis, 91.4% of the total bacterial isolates from industrial soil were found to harbour plasmids whereas 40% of the isolates from agricultural soil contained plasmids.