FKF1, a clock-controlled gene that regulates the transition to flowering in Arabidopsis

Plant reproduction requires precise control of flowering in response to environmental cues. We isolated a late-flowering Arabidopsis mutant, fkf1, that is rescued by vemalization or gibberellin treatment. We positionally cloned FKF1, which encodes a novel protein with a PAS domain similar to the flavin-binding region of certain photoreceptors, an F box characteristic of proteins that direct ubiquitin-mediated degradation, and six kelch repeats predicted to fold into a beta propeller. FKF1 mRNA levels oscillate with a circadian rhythm, and deletion of FKF1 alters the waveform of rhythmic expression of two clock-controlled genes, implicating FKF1 in modulating the Arabidopsis circadian clock.

Sediment microbial community structure and mercury methylation in mercury-polluted Clear Lake, California

Spatial and temporal variations in sediment microbial community structure in a eutrophic lake polluted with inorganic mercury were identified using polar lipid fatty acid (PLFA) analysis. Microbial community structure was strongly related to mercury methylation potential, sediment organic carbon content, and lake location. Pore water sulfate, total mercury concentrations, and organic matter C/N ratios showed no relationships with microbial community structure. Seasonal changes and changes potentially attributable to temperature regulation of bacterial membranes were detectable but were less important influences on sediment PLFA composition than were differences due to lake sampling location. Analysis of biomarker PLFAs characteristic of Desulfobacter and Desulfovibrio groups of sulfate-reducing bacteria suggests that Desulfobacter-like organisms are important mercury methylators in the sediments, especially in the Lower Arm of Clear Lake.

Phylogenetic affinity of a wide, vacuolate, nitrate-accumulating Beggiatoa sp. from Monterey Canyon, California, with Thioploca spp

Environmentally dominant members of the genus Beggiatoa and Thioploca spp. are united by unique morphological and physiological adaptations (S. C. McHatton, J. P. Barry, H. W. Jannasch, and D. C. Nelson, Appl. Environ. Microbiol. 62:954-958, 1996). These adaptations include the presence of very wide filaments (width, 12 to 160 microm), the presence of a central vacuole comprising roughly 80% of the cellular biovolume, and the capacity to internally concentrate nitrate at levels ranging from 150 to 500 mM. Until recently, the genera Beggiatoa and Thioploca were recognized and differentiated on the basis of morphology alone; they were distinguished by the fact that numerous Thioploca filaments are contained within a common polysaccharide sheath, while Beggiatoa filaments occur singly. Vacuolate Beggiatoa or Thioploca spp. can dominate a variety of marine sediments, seeps, and vents, and it has been proposed (H. Fossing, V. A. Gallardo, B. B. Jorgensen, M. Huttel, L. P. Nielsen, H. Schulz, D. E. Canfield, S. Forster, R. N. Glud, J. K. Gundersen, J. Kuver, N. B. Ramsing, A. Teske, B. Thamdrup, and O. Ulloa, Nature [London] 374:713-715, 1995) that members of the genus Thioploca are responsible for a significant portion of total marine denitrification. In order to investigate the phylogeny of an environmentally dominant Beggiatoa sp., we analyzed complete 16S rRNA gene sequence data obtained from a natural population found in Monterey Canyon cold seeps. Restriction fragment length polymorphism analysis of a clone library revealed a dominant clone, which gave rise to a putative Monterey Beggiatoa 16S rRNA sequence. Fluorescent in situ hybridization with a sequence-specific probe confirmed that this sequence originated from wide Beggiatoa filaments (width, 65 to 85 microm). A phylogenetic tree based on evolutionary distances indicated that the Monterey Beggiatoa sp. falls in the gamma subdivision of the class Proteobacteria and is most closely related to the genus Thioploca. This vacuolate Beggiatoa-Thioploca cluster and a more distantly related freshwater Beggiatoa species cluster form a distinct phylogenetic group.

Use of Reduced Sulfur Compounds by Beggiatoa spp.: Enzymology and Physiology of Marine and Freshwater Strains in Homogeneous and Gradient Cultures

The marine Beggiatoa strains MS-81-6 and MS-81-1c are filamentous, gliding, colorless sulfur bacteria. They have traditionally been cultured in very limited quantities in sulfide gradient media, where they grow as chemolithoautotrophs, forming a thin horizontal plate well below the air-agar interface. There, the facultatively chemolithoautotrophic strain MS-81-6 quantitatively harvests the flux of sulfide diffusing from below and oxidizes it to sulfate by using oxygen as the electron acceptor. Only recently have these strains been cultivated in bulk in defined liquid media (K. D. Hagen and D. C. Nelson, Appl. Environ. Microbiol. 62:947-953, 1996). In the current study, the obligately chemolithoautotrophic strain MS-81-1c was shown to have, despite much greater storage of elemental sulfur, an apparent Y(infH)(inf(inf2))(infS) twice that of MS-81-6 when the two strains were grown in identical sulfide-limited gradient media. While the basis of this difference in energy conservation has not been established, differences in sulfur oxidation enzymes were noted. Strain MS-81-1c appeared to be able to oxidize sulfite by using either the adenosine phosphosulfate (APS) pathway or a sulfite:acceptor oxidoreductase. APS pathway enzymes (ATP sulfurylase and APS reductase) were present at relatively high and constant levels regardless of growth conditions, while the sulfite:acceptor oxidoreductase activity varied at least eightfold, with the highest activity produced in sulfide gradient medium. By contrast, strain MS-81-6 showed no detectable activity of the APS pathway enzymes and possessed a sulfite:acceptor oxidoreductase activity just sufficient to account for its observed rate of growth in sulfide gradient medium. Freshwater strain OH-75-2a showed activity and regulation of sulfite:acceptor oxidoreductase consistent with lithotrophic energy conservation, a feature not yet proven for any freshwater Beggiatoa strain.

Sulfur-oxidizing symbionts have not co-evolved with their hydrothermal vent tube worm hosts: an RFLP analysis

A fine-scale phylogenetic comparison was made among the symbionts of different genera of hydrothermal vent tube worms. These included Riftia pachyptila and Tevnia jerichonona, which inhabit sites along the east Pacific Rise, and Ridgeia piscesae from the Juan de Fuca Ridge. An analysis of restriction fragment length polymorphism (RFLP) was employed using three symbiont-specific gene probes: eubacterial 16S rRNA, RuBPC/O Form II, and ATP sulfurylase (recently cloned from the Riftia symbiont). Results indicated that all of the symbionts from the three different hosts were conspecific and the Riftia and Tevnia symbionts were indistinguishable over and 1800-km range. Significantly, this indicates that the symbionts have not co-evolved with their respective hosts, which are known to belong to separate families. This study strongly supports the conclusion that the symbionts are acquired de novo by each generation of juvenile tube worms from a common source in the surrounding sea water.

Outcomes measurement and management with a large Medicaid population: a public/private collaboration

Recipients, consumer advocates and purchasers expect managed care companies, in partnership with their provider networks, to measure and to continuously improve quality of care. This task is especially challenging when the beneficiaries of that care are covered by a publicly funded program. Yet this will be an increasingly common occurrence as more states contract with managed care companies for the care management of their Medicaid populations. In this article, the authors describe the outcomes measurement and management program of the first statewide managed Medicaid behavioral health carve-out program. Much of the foundation of that program has been built through collaborative efforts between the Massachusetts Division of Medical Assistance as purchaser, MHMA as managed care vendor, recipients, providers and other stakeholders. The authors report on the FMH/MHMA experience and what they learned. The principles derived from this outcomes program may be helpful to other states and to managed care companies undertaking similar public/private partnerships.

Characterization of the gene encoding the autotrophic ATP sulfurylase from the bacterial endosymbiont of the hydrothermal vent tubeworm Riftia pachyptila

ATP sulfurylase is a key enzyme in the energy-generating sulfur oxidation pathways of many chemoautotrophic bacteria. The utilization of reduced sulfur compounds to fuel CO2 fixation by the still-uncultured bacterial endosymbionts provides the basis of nutrition in invertebrates, such as the tubeworm Riftia pachyptila, found at deep-sea hydrothermal vents. The symbiont-containing trophosome tissue contains high levels of ATP sulfurylase activity, facilitating the recent purification of the enzyme. The gene encoding the ATP sulfurylase from the Riftia symbiont (sopT) has now been cloned and sequenced by using the partial amino acid sequence of the purified protein. Characterization of the sopT gene has unequivocally shown its bacterial origin. This is the first ATP sulfurylase gene to be cloned and sequenced from a sulfur-oxidizing bacterium. The deduced amino acid sequence was compared to those of ATP sulfurylases reported from organisms which assimilate sulfate, resulting in the discovery that there is substantial homology with the Saccharomyces cerevisiae MET3 gene product but none with the products of the cysDN genes from Escherichia coli nor with the nodP and nodQ genes from Rhizobium meliloti. This and emerging evidence from other sources suggests that E. coli may be atypical, even among prokaryotic sulfate assimilators, in the enzyme it employs for adenosine 5'-phosphosulfate formation. The sopT gene probe also was shown to specifically identify chemoautotrophic bacteria which utilize ATP sulfurylase to oxidize sulfur compounds.

Keratinocyte transglutaminase expression varies in squamous cell carcinomas

Type I transglutaminase (TGase I, keratinocyte or particulate transglutaminase) is a 92-kilodalton (kDa) protein expressed in abundance in cultured keratinocytes and in the hyperproliferative skin disorder psoriasis. To determine the expression of TGase I protein and mRNA, we studied tissue and established squamous carcinoma lines derived from different sources. Immunohistochemistry and Western blotting were used to detect TGase I protein with the B.C1 mouse monoclonal antibody. Only well-differentiated, skin-derived squamous carcinomas stained for TGase I. However, a precocious pattern of expression was seen overlying less-differentiated tumors. Compared to cultured human keratinocytes, squamous cell carcinoma (SCC) had many times less to 7.8 times more TGase I protein, greatest in the two most differentiated tumor lines 14-83 and ME-180. TGase I mRNA levels ranged from 0.010 to 0.00004 pg/microgram total RNA by reverse transcriptase-polymerase chain reaction using an internal standard. Protein expression correlated with mRNA levels in most SCC lines. When a human TGase I promoter was isolated and used to study genomic DNA, SCC1-83 was shown to have unique restriction enzyme fragments, including one indicative of methylation differences, also present within DNA from the KB line. These studies suggest that transcriptional control of TGase I gene expression in squamous carcinomas may be influenced both by cis elements in the promoter and by the degree of tumor squamous differentiation.

ATP sulfurylase from trophosome tissue of Riftia pachyptila (hydrothermal vent tube worm)

ATP sulfurylase (ATP: sulfate adenylyltransferase, EC 2.7.7.4) was extensively purified from trophosome tissue of Riftia pachyptila, a tube worm that thrives in deep ocean hydrothermal vent communities. The enzyme is probably derived from the sulfide-oxidizing bacteria that densely colonize the tissue. Glycerol (20% v/v) protected the enzyme against inactivation during purification and storage. The native enzyme appears to be a dimer (MW 90 kDa +/- 10%) composed of identical size subunits (MW 48 kDa +/- 5%). At pH 8.0, 30 degrees C, the specific activities (units x mg protein-1) of the most highly purified sample are as follows: ATP synthesis, 370; APS synthesis, 23; molybdolysis, 65; APSe synthesis or selenolysis, 1.9. The Km values for APS and PPi at 5 mM Mg2+ are 6.3 and 14 microM, respectively. In the APS synthesis direction, the Km values for MgATP and SO4(2-) are 1.7 and 27 mM, respectively. The Km values for MgATP and MoO4(2-) in the molybdolysis reaction are 80 and 150 microM, respectively. The Kia for MgATP is 0.65 mM. APS is a potent inhibitor of molybdolysis, competitive with both MgATP and MoO4(2-) (Kiq = 2.2 microM). However, PPi (+ Mg2+) is virtually inactive as a molybdolysis inhibitor. Oxyanion dead end inhibitors competitive with SO4(2-) include (in order of decreasing potency) ClO4- greater than FSO3- (Ki = 22 microM) greater than ClO3- greater than NO3- greater than S2O3(2-) (Ki's = 5 and 43 mM). FSO3- is uncompetitive with MgATP, but S2O3(2-) is noncompetitive. Each subunit contains two free SH groups, at least one of which is functionally essential. ATP, MgATP, SO4(2-), MoO4(2-), and APS each protect against inactivation by excess 5,5'-dithiobis-(2-nitrobenzoate). FSO3- is ineffective as a protector unless MgATP is present. PPi (+Mg2+) does not protect against inactivation. Riftia trophosome contains little or no "ADP sulfurylase." The high trophosome level of ATP sulfurylase (67-176 ATP synthesis units x g fresh wt tissue-1 from four different specimens, corresponding to 4-10 microM enzyme sites), the high kcat of the enzyme for ATP synthesis (296 s-1), and the high Km's for MgATP and SO4(2-) are consistent with a role in ATP formation during sulfide oxidation, i.e., the physiological reaction is APS + MgPPi in equilibrium SO4(2-) + MgATP.

DNA-DNA Solution Hybridization Studies of the Bacterial Symbionts of Hydrothermal Vent Tube Worms ( Riftia pachyptila and Tevnia jerichonana )

The giant tube worm, Riftia pachyptila (phylum Vestimentifera), is known only from four widely separated sulfide-rich deep-sea hydrothermal vent systems. This invertebrate is nourished by intracellular, chemoautotrophic bacterial symbionts which reside in a specialized trophosome tissue. The symbiont has not been cultured independently and is believed to be acquired de novo by host larvae of each generation. In the current study, R. pachyptila symbiont DNA was purified from the two most distant sites on the basis of its difference in density versus host DNA. These two standards were hybridized against trophosome DNAs of 13 individuals from the Guaymas Basin, Galapagos Rift, and 13°N vents. This indicated that all R. pachyptila symbionts are conspecific and that the variability in DNA-DNA hybridization (relative binding ratio [RBR]) was comparable within or between widely separated vents. The symbiont of another tube worm, Tevnia jerichonana , was found to be the same as that of R. pachyptila , the first case in which distinct hosts possess the same sulfur bacterial symbiont. By contrast, Lamellibrachia sp. (same class as T. jerichonana ) showed insignificant RBR with the R. pachyptila symbiont. DNA derived from solely eucaryotic tissue of R. pachyptila showed a surprisingly high RBR (20 to 50) with density-separated DNA standards. With DNAs obtained from physically separated symbionts, independent solution hybridization experiments confirmed the above-described conclusions. Possible explanations for this host-symbiont homology are discussed.

Characterization of Large, Autotrophic Beggiatoa spp. Abundant at Hydrothermal Vents of the Guaymas Basin

Filamentous bacteria, identified as members of the genus Beggiatoa by gliding motility and internal globules of elemental sulfur, occur in massive aggregations at the deep-sea hydrothermal vents of the Guaymas Basin, Gulf of California. Cell aggregates covering the surface of sulfide-emanating sediments and rock chimneys were collected by DS R/V Alvin and subjected to shipboard and laboratory experiments. Each sample collected contained one to three discrete width classes of this organism usually accompanied by a small number of “flexibacteria” (width, 1.5 to 4 μm). The average widths of the Beggiatoa classes were 24 to 32, 40 to 42, and 116 to 122 μm. As indicated by electron microscopy and cell volume/protein ratios, the dominant bacteria are hollow cells, i.e., a thin layer of cytoplasm surrounding a large central liquid vacuole. Activities of Calvin-cycle enzymes indicated that at least two of the classes collected possess autotrophic potential. Judging from temperature dependence of enzyme activities and whole-cell CO 2 incorporation, the widest cells were mesophiles. The narrowest Beggiatoa sp. was either moderately thermophilic or mesophilic with unusually thermotolerant enzymes. This was consistent with its occurrence on the flanks of hot smoker chimneys with highly variable exit temperatures. In situ CO 2 fixation rates, sulfide stimulation of incorporation, and autoradiographic studies suggest that these Beggiatoa spp. contribute significantly as lithoautrophic primary producers to the Guaymas Basin vent ecosystems.

Bacterial zonation, photosynthesis, and spectral light distribution in hot spring microbial mats of Iceland

The zonation and structure of phototrophic microbial mats were studied along two thermal gradients in sulfide-rich hot springs of southwest Iceland. The green, filamentous bacteriumChloroflexus and the unicellular, "high-temperature form" (HTF) ofMastigocladus formed mats growing up to a temperature limit of 62-66°C. The dominant phototrophs wereChloroflexus sp.,Mastigocladus laminosus, andPhormidium laminosum, respectively, at the three temperature intervals: >60°C, 60°C to 55-50°C, and <55-50°C. AChloroflexus mat growing at 60°C under 60μM H2S was anoxic in the light with the exception of a 0.5 mm thick band of HTFMastigocladus which produced oxygen. The oxygenic photosynthesis of these H2S-sensitive cyanobacteria was probably dependent on a preceding sulfide depletion by the anoxygenicChloroflexus. Measurements of spectral radiance gradients with a fiberoptic microprobe showed maximum light attenuation by carotenoids and bacteriochlorophyllC. AM. laminosus mat growing at 52°C was oxic throughout and showed maximum light attenuation by carotenoids, chlorophyllA, and phycocyanin, but no detectable phycoerythrocyanin absorption.

Growth Pattern and Yield of a Chemoautotrophic Beggiatoa sp. in Oxygen-Sulfide Microgradients

Recently developed techniques involving opposed, gel-stabilized gradients of O 2 and H 2 S permit cultivation of a marine Beggiatoa strain as a chemolithoautotroph which uses gliding motility to precisely track the interface between H 2 S and O 2 . In the current study with microelectrodes, vertical profiles of H 2 , O 2 , and pH were measured in replicate cultures grown for various intervals. After an initial period of exponential biomass increase (doubling time, 11 h), linear growth prevailed throughout much of the time course. This H 2 S-limited growth was followed by a transition to stationary phase when the declining H 2 S flux was sufficient only to supply maintenance energy. During late-exponential and linear growth phases, the Beggiatoa sp. consumed a constant 0.6 mol of H 2 S for each 1.0 mol of O 2 , the ratio anticipated for balanced lithoautotrophic growth at the expense of complete oxidation of H 2 S to SO 4 2− . Over the entire range of conditions studied, this consumption ratio varied by approximately twofold. By measuring the extent to which the presence of the bacterial plate diminished the overlap of O 2 and H 2 S, we demonstrated that oxidation of H 2 S by Beggiatoa sp. is approximately 3 orders of magnitude faster than spontaneous chemical oxidation. By integrating sulfide profiles and comparing sulfide consumed with biomass produced, a growth yield of 8.4 g (dry weight) mol −1 of H 2 S was computed. This is higher than that found for sulfide-grown thiobacilli, indicating very efficient growth of Beggiatoa sp. as a chemoautotroph. The methods used here offer a unique opportunity to determine the yield of H 2 S-oxidizing chemolithoautotrophs while avoiding several problems inherent in the use of homogeneous liquid culture. Finally, by monitoring time-dependent formation of H 2 S profiles under anoxic conditions, we demonstrate a method for calculating the molecular diffusion coefficient of soluble substrates in gel-stabilized media.

The effect of cimetidine on hepatic drug elimination in cirrhosis

Both cimetidine therapy and cirrhosis individually interfere with normal elimination of various drugs. Cimetidine is often prescribed in patients with cirrhosis but there is incomplete data on its effect on drug elimination in cirrhotics. The purpose of this study was to address this issue. Eight stable cirrhotics were studied prior to and following 7 days of cimetidine administration, (300 mg orally q.i.d.). Chlordiazepoxide (Librium), which is eliminated by the liver after demethylation, and indocyanine green, which is removed by the liver without biotransformation, were used as probes. Consistent with the concept that cimetidine interferes with drug metabolism by inhibiting microsomal oxidation, chlordiazepoxide clearance in the cirrhotics was inhibited by cimetidine (p less than 0.05), but indocyanine green clearance was unaffected. As shown by us previously (Roberts, R. K. et al., Gastroenterology 1978; 75:479-485), untreated cirrhotics had substantially lower chlordiazepoxide clearance than did controls. The inhibitory effect of cimetidine on chlordiazepoxide clearance was less in cirrhotics than in controls (p less than 0.05). In all subjects, there was excellent correlation between initial clearance and magnitude of depression in clearance after cimetidine, i.e., the larger the initial clearance, the larger the change (r = 0.97, p less than 0.0001). Forty-eight hours after stopping cimetidine, chlordiazepoxide clearance returned to baseline in cirrhotics and controls. Our data demonstrate that cimetidine and cirrhosis may act additively to impair drug metabolism. This effect of cimetidine on chlordiazepoxide clearance is smaller in cirrhotics than in controls, but, because of impaired initial drug elimination in cirrhosis, it may result in adverse clinical effects.

Hypernatremia and lactulose therapy

Lactulose is used in the treatment of portal-systemic encephalopathy. Although it is usually safe, a case of hypernatremia has been reported. To evaluate further the association of lactulose therapy and hypernatremia, records of patients with hepatic failure treated with lactulose for encephalopathy were analyzed. In 20 of 75 courses of lactulose treatment, serum sodium level exceeded 145 mEq/L. Mortality was 41% in patients in whom hypernatremia developed as compared with 14% in those who remained normonatremic. In persons who died, hypernatremia persisted; in patients who eventually recovered, the serum sodium level returned to normal. The precise mechanism of hypernatremia in these cases is not clearly defined. As an osmotic cathartic, however, lactulose may cause fecal water loss in excess of sodium, resulting in contraction of extracellular fluid volume and, therefore, hypernatremia.

Dermal penetration and potential for placental transfer of the insect repellent, N,N-diethyl-m-toluamide

N,N-Diethyl-m-toluamide (m-Det) is a widely used insect repellent readily available in various formulations. Radiolabeled (14C) m-Det was evaluated for rate and extent of skin penetration in three animal species. Absorption was quantitated in excreta for 7 days following a single dermal application and deposition monitored in tissues at necropsy. The potential for transplacental transfer and bioaccumulation of absorbed m-Det the fetus was also assessed following repeated applications to pregnant rabbits. Significant dermal absorption of the repellent was noted in all species, primarily in the first few hours, and was essentially complete after 3 days. No bioaccumulation of the labeled moiety was noted in tissues at 7 days. Pregnant rabbits receiving repeated dermal applications throughout gestation showed no evidence of bioaccumulation of the chemical in maternal tissue or individual fetuses. It is suggested that m-Det should not present a dermatoxic hazard to man and that topical absorption should be less than 10% of the applied dose.

Organic nutrition of Beggiatoa sp

Culture OH-75-B of Beggiatoa sp. differed significantly from any described previously in its utilization of organic carbon and reduced sulfur compounds. It deposited internal sulfur granules characteristic of Beggiatoa sp. with either sulfide or thiosulfate in the medium. This strain (OH-75-B, clone 2a) could be grown in agitated liquid cultures on mineral medium with acetate as the only source of organic carbon. The resultant growth yields and rates were comparable to those for typical heterotrophs. Of the other simple organic compounds tested, only pyruvate, lactate, or ethanol could singly support the growth of this strain. Single sugars or amino acids neither supported growth nor enhanced it when added to acetate-containing medium. In contrast, compounds of the tricarboxylic acid cycle enhanced growth yields when tested in concert with acetate. These and fluoroacetate inhibition results indicate that Beggiatoa sp. possesses a functional tricarboxylic acid cycle. Poor yields characterized the growth of this strain on dilute yeast extract medium, and higher concentrations of yeast extract proved inhibitory. The enzyme catalase, contrary to the findings of others, had no synergistic influence on growth yields when added to medium containing yeast extract or acetate or both.

Use of reduced sulfur compounds by Beggiatoa sp

A strain of Beggiatoa cf. leptomitiformis (OH-75-B, clone 2a) was isolated which is unique among reported strains in its ability to deposit internal sulfur granules from thiosulfate. It also deposited these characteristic granules (as all BEggiatoa species do) from sulfide. In cultures where growth was limited by exhaustion of organic substrates, these granules generally comprised about 20% of the total cell weight. With medium containing acetate and thiosulfate, no measurable utilization of thiosulfate or deposition of elemental sulfur (S0) took place until after the exponential growth phase. Neither sulfide nor thiosulfate added an increment to heterotrophic growth yield except for the weight of the deposited S0. The deposition of S0 from thiosulfate was probably a disproportionation in which S0 and sulfate were produced in a 1:1 ratio. Some of the S0 was further oxidized to sulfate. No autotrophic or mixotrophic growth was demonstrated for this strain. When inoculated in small, well-dispersed quantities into yeast extract medium, this strain grew only after long lags. Addition of the enzyme catalase eliminated initial lags and increased growth rates slightly. In contrast, catalase had no influence on growth rate when added to mineral medium containing acetate. In yeast extract medium, the inhibition of growth rate was presumably because of peroxides. Addition of thiosulfate was almost as effective as catalase in eliminating this inhibition. The S0 granules which, in this case, were deposited during the exponential growth phase, appeared to be partly responsible for this relief. This strain of Beggiatoa sp. remained active for at least 5 days under strictly anaerobic conditions, and under those conditions, it increased its dry weight by about 2.5-fold. Anaerobic "growth" and maintenance required the presence of an energy source, such as acetate. When cells containing much internal S0 were transferred to an organic anaerobic medium, a substantial portion of the internal S0 was eventually converted to sulfide.

Renal vein thrombosis associated with nephrotic syndrome and gold therapy in rheumatoid arthritis

In this case of renal vein thrombosis secondary to a nephrotic syndrome, we postulate renal disease resulted from gold therapy. We know of no previous report relating gold toxicity and renal vein thrombosis. It should be emphasized that with increasing use of gold, proteinuria and nephrotic syndrome may be more common than once suspected and, when present, predispose to the development of renal vein thrombosis.

A direct-reading comparison spectroradiometer

A modification of the Cary Model 14 for radiometry is described which allows recording in microwatts per square mlllimeter per nanometer on the ordinate and linear wavelength on the abscissa through the range 250-2500 nm. A 5.08-cm diam rotating integrating sphere is used to compare standard to unknown sources at a 30 c/s rate. The undispersed radiation from the sphere is directed through the entrance slit of the monochromator. After dispersion by the monochromator the energy is received by a single phototube or PbS detector as alternate pulses of standard and unknown energy. This design results in common optical elements throughout the instrument except for the standard and unknown sources themselves. An electrical calibration system permits an ordinate scale reading irradiance directly in microwatts per square centimeter per nanometer with simple provisions for range change. The instrument provides a dynamic range of 2 x 10(6) to 1. A large open area is provided for mounting unknown sources. The entrance optical system is designed so that remote sources can be viewed conveniently.