Caves as a key habitat for rare and endemic species of the west coast of North America: a taxonomic revision of the spider genus Oaphantes (Araneae: Linyphiidae).

The genus Oaphantes is known from the West Coast of North America. Here we revise the genus which now includes three species, two of which are new: O. cryophilus n. sp. and O. prometheus n. sp. All Members of the genus Oaphantes show affinities for cave habitats. Oaphantes pallidulus is known from caves of the Coast Ranges of California and also from epigean records. Oaphantes cryophilus n. sp. is restricted to caves in the southern limit of its distribution in the Sierra Nevada Mountains of California, but in the north it is known from epigean records in Oregon, Washington and British Columbia. Oaphantes prometheus n. sp. is an eyeless troglobite endemic to a single cave in the Sierra Nevada of California. The distribution and relationships of the three species suggest an evolutive scenario likely due to climatic variations and affinities for colder conditions.

The power and perils of 'molecular taxonomy': a case study of eyeless and endangered Cicurina (Araneae: Dictynidae) from Texas caves.

Rapid development in karst-rich regions of the US state of Texas has prompted the listing of four Cicurina species (Araneae, Dictynidae) as US Federally Endangered. A major constraint in the management of these taxa is the extreme rarity of adult specimens, which are required for accurate species identification. We report a first attempt at using mitochondrial DNA (mtDNA) sequences to accurately identify immature Cicurina specimens. This identification is founded on a phylogenetic framework that is anchored by identified adult and/or topotypic specimens. Analysis of approximately 1 kb of cytochrome oxidase subunit I (CO1) mtDNA data for over 100 samples results in a phylogenetic tree that includes a large number of distinctive, easily recognizable, tip clades. These tip clades almost always correspond to a priori species hypotheses, and show nonoverlapping patterns of sequence divergence, making it possible to place species names on a number of immature specimens. Three cases of inconsistency between recovered tip clades and a priori species hypotheses suggest possible introgression between cave-dwelling Cicurina, or alternatively, species synonymy. Although species determination is not possible in these instances, the inconsistencies point to areas of taxonomic ambiguity that require further study. Our molecular phylogenetic sample is largest for the Federally Endangered C. madla. These data suggest that C. madla occurs in more than twice the number of caves as previously reported, and indicate the possible synonymy of C. madla with C. vespera, which is also Federally Endangered. Network analyses reveal considerable genetic divergence and structuring across caves in this species. Although the use of DNA sequences to identify previously 'unidentifiable' specimens illustrates the potential power of molecular data in taxonomy, many other aspects of the same dataset speak to the necessity of a balanced taxonomic approach.

Inactivation of foodborne pathogens in milk using dynamic high pressure.

Improving the microbiological safety of perishable foods is currently a major preoccupation in the food industry. The aim of this study was to investigate the inactivation of three major food pathogens (Listeria monocytogenes [LSD 105-1], Escherichia coli O157:H7 [ATCC 35150], and Salmonella enterica serotype Enteritidis ATCC [13047]) by dynamic high pressure (DHP) in order to evaluate its potential as a new alternative for the cold pasteurization of milk. The effectiveness of DHP treatment against L. monocYtogenes, E. coli O157:H7, and Salmonella Enteritidis was first evaluated in 0.01 M phosphate-buffered saline (PBS) at pH 7.2 as a function of applied pressure (100, 200, and 300 MPa) and of the number of passes (1, 3, and 5) at 25 degrees C. A single pass at 100 MPa produced no significant inactivation of the three pathogens, while increasing the pressure up to 300 MPa or the number of passes to five increased inactivation. From an initial count of 8.3 log CFU/ml, complete inactivation of viable L. monocytogenes was achieved after three successive passes at 300 MPa, while 200-MPa treatments with three and five passes completely eliminated viable Salmonella Enteritidis and E. coli O157:H7, respectively. The effectiveness of DHP for the inactivation of these pathogens was compared to that of hydrostatic high pressure (HHP) using the same pressure (200 MPa, single pass at 25 degrees C). In general, two additional log reductions in viable count were obtained with DHP DHP was less effective against L. monocytogenes and E. coli O157:H7 in raw milk than in PBS. After five passes at 200 MPa, an 8.3-log reduction was obtained for E. coli O157:H7, while a reduction of about 5.8 log CFU/ml was obtained for L. monocytogenes exposed to 300 MPa for five passes. Exposing milk or buffer samples to mild heating (45 to 60 degrees C) prior to dynamic pressurization enhanced the lethal effect of DHP The inactivation of pathogens also depended on the initial bacterial concentration. The highest reduction was obtained when the bacterial load did not exceed 10(5) CFU/ml. In conclusion, DHP was shown to be very effective for the destruction of the tested pathogens. It offers a promising alternative for the cold pasteurization of milk and possibly other liquid foods.

Biotic ligand model of the acute toxicity of metals. 1. Technical basis.

The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal-biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal-DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount.

Biotic ligand model of the acute toxicity of metals. 2. Application to acute copper toxicity in freshwater fish and Daphnia.

The biotic ligand model (BLM) was developed to explain and predict the effects of water chemistry on the acute toxicity of metals to aquatic organisms. The biotic ligand is defined as a specific receptor within an organism where metal complexation leads to acute toxicity. The BLM is designed to predict metal interactions at the biotic ligand within the context of aqueous metal speciation and competitive binding of protective cations such as calcium. Toxicity is defined as accumulation of metal at the biotic ligand at or above a critical threshold concentration. This modeling framework provides mechanistic explanations for the observed effects of aqueous ligands, such as natural organic matter, and water hardness on metal toxicity. In this paper, the development of a copper version of the BLM is described. The calibrated model is then used to calculate LC50 (the lethal concentration for 50% of test organisms) and is evaluated by comparison with published toxicity data sets for freshwater fish (fathead minnow, Pimephales promelas) and Daphnia.

Uniaxial compression of thermal gels based on microfluidized blends of WPI and heat-denatured WPI.

The effect of heat-denatured whey protein isolate (dWPI)/whey protein isolate (WPI) ratio (0-0.6), microfluidization pressure (0-1000 bar), and number of passes (1-10) on the uniaxial shear stress at 10% (sigma(10)) and 80% (sigma(80)) relative deformation of dWPI/WPI heat-induced gels (14% total protein, w/w) was studied. No correlation between the average diameter of aggregates and the dWPI/WPI ratio, microfluidization pressure, or number of passes was found. However, increasing the microfluidization pressure or the number of passes resulted in a narrower size distribution of aggregates. Increasing the dWPI/WPI ratio and the number of passes resulted in a decrease and an increase of gel hardness, respectively. The results were interpreted in terms of more random aggregation/gelation of proteins in the presence of aggregates that could result in localized heterogeneities into gels and more dissipation of the deformation energy during compression. The positive effect of the number of passes on the gel hardness was also considered to be due to a more homogeneous aggregation/gelation of proteins in the presence of smaller aggregates.

Near-infrared analysis of fat, protein, and casein in cow's milk.

Fat, crude protein, true protein, and casein were determined in cow milks by near-infrared transmission spectroscopy (NIR). Partial and overall PLS calibrations were performed on two sets of samples: partial calibration included 76 unhomogenized samples, whereas overall calibration used 96 homogenized and unhomogenized samples. Standard errors of calibration were 0.12% for fat, 0.06% for crude protein, 0.04% for true protein, and 0.05% for casein in the overall calibration. Validation of the overall calibration with an independent set of samples gave standard errors of prediction of 0. 07% for fat, 0.06% for crude protein and casein, and 0.05% for true protein. Except for fat, all of the statistical parameters were better with overall than with partial calibrations, which indicates that homogenization has an effect on NIR fat determination. Despite the relatively small number of samples included in the calibration model, NIR transmission was found to be a reliable method for the determination of fat and nitrogenous constituents in milk.

Relationships between conformation of beta-lactoglobulin in solution and gel states as revealed by attenuated total reflection Fourier transform infrared spectroscopy.

Attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) has been used to compare the structure of beta-lactoglobulin, the major component of whey proteins, in solution and in its functional gel state. To induce variation in the conformation of beta-lactoglobulin under a set of gelling conditions, the effect of heating temperature, pH, and high pressure homogenization on the conformation sensitive amide I band in the infrared spectra of both solutions and gels has been investigated. The results showed that gelification process has a pronounced effect upon beta-lactoglobulin secondary structure, leading to the formation of intermolecular hydrogen-bonding beta-sheet structure as evidenced by the appearance of a strong band at 1614 cm(-1) at the expense of other regular structures. These results confirm that this structure may be essential for the formation of a gel network as it was previously shown for other globular proteins. However, this study reveals, for the first time, that there is a close relationship between conformation of beta-lactoglobulin in solution and its capacity to form a gel. Indeed, it is shown that conditions which promote predominance of intermolecular beta-sheet in solution such as pH 4, prevent the formation of gel in conditions used by increasing thermal stability of beta-lactoglobulin. On the basis of these findings, it is suggested that by controlling the extent of intermolecular beta-structure of the protein in solution, it is possible to modify the ability of protein to form a gel and as a consequence to control the properties of gels.

Experiments on the heat-induced salt balance changes in cow's milk.

The heat-induced changes in salt balance between the colloidal phase of milk and its serum were studied using an ultrafiltration technique. Milk permeate was isolated at the heating temperature by means of a hollow fibre ultrafiltration cartridge coupled with a stainless steel heat exchanger unit. The milk samples initially at 4 degrees C were heated to 20, 40, 60, 80 or 90 degrees C. Ca, P, Mg and citrate contents of the permeates were determined. The decreases in Ca and P were proportional to the increase in temperature. Smaller losses in Mg and citrate were observed. An initial sharp decrease in concentration occurred within the first seconds of holding time and was followed by a slower and smaller decrease. The possible occurrence of a two-stage mechanism for the heat-induced salt precipitation is discussed. The precipitation of dicalcium phosphate is believed to occur together with some tricalcium citrate precipitation.

Photoacoustic analysis of some milk products in ultraviolet and visible light.

The research reported here demonstrates the possibility of using photoacoustic spectroscopy for milk product analysis. Milk products including yogurt, cheese, and market milk were analyzed in the ultraviolet visible range. A strong absorption peak was present at 280 nm for all the products. Relationship was linear between relative protein concentration of skim milk and the photoacoustic signal at 280 nm (r2 greater than .99). Powdered milks, prepared from skim milk that had been subjected to different heat treatments before drying, were analyzed, and a second absorption peak at 335 nm was noted for milks subjected to high heat treatment prior to the drying process. This second absorption peak appears associated with Maillard reaction products. Analysis of stored UHT heat-treated milk and infant formulas showed a similar peak at 335 nm. The results suggest that the Maillard reaction is initiated during UHT treatment of milk, and associated pigments develop only during storage. The presence of the 335-nm band in the photoacoustic spectra of infant formulas is considered as the result of heat sterilization. It is anticipated that as photoacoustic spectroscopy becomes more common, its usefulness in the milk industry, in particular, and in food science, in general, will increase.

Formation of asymmetrical planar lipid bilayer membranes from characterized monolayers.

A device allowing the formation of lipid bilayers by apposition of characterized monolayers has been designed and constructed. It is essentially composed of two solid Teflon Langmuir troughs, pressed along one another. The troughs are both equipped with a movable barrier for the compression of the monolayers and a float-type torsion balance for the detection of the surface pressures. The lipid bilayers are formed across a tiny hole (0.225 mm diameter) punched through a polymer film clamped in between the two troughs and are characterized by their electrical properties (specific resistance and capacitance). Experimental results have been obtained on asymmetrical membranes of phosphatidylethanolamine and phosphatidylserine formed from monolayers and from lipid films many molecular dimensions in thickness. Two polymer supports, Teflon and polypropylene, were used and coated with either squalene or petroleum jelly. The results show that the stability of the bilayer, particularly when formed from monolayers, is a direct function of the interactions of the lipids with the coated support. The most stable membranes are obtained when Teflon is used as support and squalene as coating. The most important advantage of the technique presented here is found when the bilayers are formed from mixtures of components deposited at the interface. Indeed, our system allows a characterization of the miscibility of the components in the monolayers prior to form the membrane, as opposed to a complete ignorance of the molecular organization when the bilayers are formed by apposing lipid films.