A family with X-linked deafness showing linkage to the proximal Xq region of the X chromosome

Linkage analysis has been carried out in a family with severe congenital sensorineural deafness with a structural abnormality of the inner ear. Recombinations show the gene responsible for deafness in this family to lie between the loci DXS255 (Xp11.22) and DXS94 (Xq22). Close linkage was found to locus DXS159 (cpX289) in Xq12, with a LOD score of 3.155 and 0 recombination. This location is consistent with other linkage studies of X-linked deafness.     

Aerobic mineralization of vinyl chloride by a bacterium of the order Actinomycetales.

A gram-positive branched bacterium isolated from a trichloroethylene-degrading consortium mineralized vinyl chloride in growing cultures and cell suspensions. Greater than 67% of the [1,2-14C]vinyl chloride was mineralized to carbon dioxide, with approximately 10% of the radioactivity appearing in cell biomass and another 10% appearing in 14C-aqueous-phase products.     

Changes in Fructose 2,6-Bisphosphate Levels in Green Pepper (Capsicum annuum L.) Fruit in Response to Temperature

The regulatory metabolite, fructose 2,6-bisphosphate (Fru 2,6-P₂) was found in green pepper (Capsicum annuum L.). The Fru 2,6-P₂ level was found to: (a) rise rapidly in response to heat; (b) drop rapidly, followed by recovery, in response to cold storage of fruit and, (c) oscillate during cold storage of fruit. The possible existence of a relationship between chilling injury and Fru 2,6-P₂ is considered.     

Neural networks predict response biases of female túngara frogs.

Artificial neural networks have become useful tools for probing the origins of perceptual biases in the absence of explicit information on underlying neuronal substrates. Preceding studies have shown that neural networks selected to recognize or discriminate simple patterns may possess emergent biases toward pattern size of symmetry--preferences often exhibited by real females--and have investigated how these biases shape signal evolution. We asked whether simple neural networks could evolve to respond to an actual mate recognition signal, the call of the túngara frog, Physalaemus pustulosus. We found that not only were networks capable of recognizing the call of the túngara frog, but that they made remarkably accurate quantitative predictions about how well females generalized to many novel calls, and that these predictions were stable over several architectures. The data suggest that the degree to which P. pustulosus females respond to a call may often be an incidental by-product of a sensory system selected simply for species recognition.     

Isolation from estuarine sediments of a Desulfovibrio strain which can grow on lactate coupled to the reductive dehalogenation of 2,4, 6-tribromophenol

Strain TBP-1, an anaerobic bacterium capable of reductively dehalogenating 2,4,6-tribromophenol to phenol, was isolated from estuarine sediments of the Arthur Kill in the New York/New Jersey harbor. It is a gram-negative, motile, vibrio-shaped, obligate anaerobe which grows on lactate, pyruvate, hydrogen, and fumarate when provided sulfate as an electron acceptor. The organism accumulates acetate when grown on lactate and sulfate, contains desulfoviridin, and will not grow in the absence of NaCl. It will not utilize acetate, succinate, propionate, or butyrate for growth via sulfate reduction. When supplied with lactate as an electron donor, strain TBP-1 will utilize sulfate, sulfite, sulfur, and thiosulfate for growth but not nitrate, fumarate, or acrylate. This organism debrominates 2-, 4-, 2,4-, 2,6-, and 2,4,6-bromophenol but not 3- or 2,3-bromophenol or monobrominated benzoates. It will not dehalogenate monochlorinated, fluorinated, or iodinated phenols or chlorinated benzoates. Together with its physiological characteristics, its 16S rRNA gene sequence places it in the genus Desulfovibrio. The average growth yield of strain TBP-1 grown on a defined medium supplemented with lactate and 2,4,6-bromophenol is 3.71 mg of protein/mmol of phenol produced, and the yield was 1.42 mg of protein/mmol of phenol produced when 4-bromophenol was the electron acceptor. Average growth yields (milligrams of protein per millimole of electrons utilized) for Desulfovibrio sp. strain TBP-1 grown with 2,4,6-bromophenol, 4-bromophenol, or sulfate are 0.62, 0.71, and 1.07, respectively. Growth did not occur when either lactate or 2,4,6-bromophenol was omitted from the growth medium. These results indicate that Desulfovibrio sp. strain TBP-1 is capable of growth via halorespiration.     

Sensitive Enzymatic Assay for Glucose Determination in Natural Waters

A new enzymatic method for glucose determination is described. It allows measurement of glucose concentration as low as 10^-7 M. Such sensitivity makes this method particularly appropriate for estimation of glucose in natural-water bodies, generally without prior concentration or extraction. The method is based on the reaction between glucose and adenosine 5′-triphosphate, catalyzed by hexokinase to form glucose-6-phosphate. The amount of adenosine 5′-triphosphate consumed in this reaction, which is directly proportional to the amount of glucose present in the sample, is measured by the luciferin-luciferase assay. The optimal conditions for glucose determination by this method have been defined as follows: 20 min of incubation at 30°C, magnesium concentration of 10^-3 M, and pH in the range of 7.5 to 10.5. The specificity of the assay to different carbohydrates has also been studied. Recovery of known amounts of glucose added to Lake Kinneret water was in the range of 80 to 114%. Application of this method is demonstrated in eight monthly profiles of the glucose content in Lake Kinneret.     

13C-Carrier DNA Shortens the Incubation Time Needed To Detect Benzoate-Utilizing Denitrifying Bacteria by Stable-Isotope Probing

The active bacterial community able to utilize benzoate under denitrifying conditions was elucidated in two coastal sediments using stable-isotope probing (SIP) and nosZ gene amplification. The SIP method employed samples from Norfolk Harbor, Virginia, and a Long-Term Ecosystem Observatory (no. 15) off the coast of Tuckerton, New Jersey. The SIP method was modified by use of archaeal carrier DNA in the density gradient separation. The carrier DNA significantly reduced the incubation time necessary to detect the ¹³C-labeled bacterial DNA from weeks to hours in the coastal enrichments. No denitrifier DNA was found to contaminate the archaeal ¹³C-carrier when [¹²C]benzoate was used as a substrate in the sediment enrichments. Shifts in the activity of the benzoate-utilizing denitrifying population could be detected throughout a 21-day incubation. These results suggest that temporal analysis using SIP can be used to illustrate the initial biodegrader(s) in a bacterial population and to document the cross-feeding microbial community.     

Micron-pore-sized metallic filter tube membranes for filtration of particulates and water purification

Robust filtering techniques capable of efficiently removing particulates and biological agents from water or air suffer from plugging, poor rejuvenation, low permeance, and high backpressure. Operational characteristics of pressure-driven separations are in part controlled by the membrane pore size, charge of particulates, transmembrane pressure and the requirement for sufficient water flux to overcome fouling. With long term use filters decline in permeance due to filter-cake plugging of pores, fouling, or filter deterioration. Though metallic filter tube development at ORNL has focused almost exclusively on gas separations, a small study examined the applicability of these membranes for tangential filtering of aqueous suspensions of bacterial-sized particles. A mixture of fluorescent polystyrene microspheres ranging in size from 0.5 to 6 microm in diameter simulated microorganisms in filtration studies. Compared to a commercial filter, the ORNL 0.6 microm filter averaged approximately 10-fold greater filtration efficiency of the small particles, several-fold greater permeance after considerable use and it returned to approximately 85% of the initial flow upon backflushing versus 30% for the commercial filter. After filtering several liters of the particle-containing suspension, the ORNL composite filter still exhibited greater than 50% of its initial permeance while the commercial filter had decreased to less than 20%. When considering a greater filtration efficiency, greater permeance per unit mass, greater percentage of rejuvenation upon backflushing (up to 3-fold), and likely greater performance with extended use, the ORNL 0.6 microm filters can potentially outperform the commercial filter by factors of 100-1,000 fold.     

Anaerobic Mineralization of Stable-Isotope-Labeled 2-Methylnaphthalene

An active sulfate-reducing consortium that degrades 2-methylnaphthalene (2-MNAP) at rates of up to 25 μM day⁻¹ was established. Degradation was inhibited in the presence of molybdate and ceased in the absence of sulfate. As much as 87% of 2-[¹⁴C]MNAP was mineralized to ¹⁴CO₂. 2-Naphthoic acid (2-NA) was detected as a metabolite, and incubation with either deuterated 2-MNAP or [¹³C]bicarbonate indicates that 2-NA is the result of oxidation of the methyl group. Also detected were carboxylated 2-MNAPs, suggesting the presence of an alternative pathway for 2-MNAP degradation.