Distribution of euphausiid and decapod larvae in the spring plankton of the southern Barents Sea

New data have been obtained on the spatial distribution of the early developmental stages of Malacostraca in the mesozooplankton of the southern Barents Sea. In spring 2007, the euphausiid stages with the highest abundance (over 80%) were eggs and nauplii. Decapod larvae were represented by zoeae of Paralithodes camtschaticus, Pagurus pubescens, and Hyas araneus; their abundance was at most 1.5% of total zooplankton abundance. The larvaton groups dominant by abundance were furciliae of Euphasiacea (14.5 ± 6.2 mg/m³) and zoeae of P. camtschaticus (32.7 ± 15.9 mg/m³). The size structure of larval hemipopulations was similar over the studied water area. Comparison with data on the larval body length obtained in other areas of the sea leads to a conclusion on the independence of the decapod groups of Eastern and Western Murman.     

A new method for measuring sulfotransferase

Agarose can be activated by adding cyanogen bromide, dissolved in acetonitrile, to beads suspended in a solution of sodium carbonate. The necessity for manual titration and the use of a pH meter are thus eliminated. Activation for 1 min results in coupling capacities comparable to those reported for the titration method. The coupling capacity is influenced by the initial carbonate concentration and by the duration and temperature of the activation reaction. The coupling capacities of the activated gels are very reproducible.     

A method for measuring microquantities of DNA

Quantitative analysis of DNA content represents a critical step when only very small amounts of nucleic acids are available. The DNA content of a small RNA-free sample can be measured in a simple and precise way using a two-dimensional approach. DNA samples are spotted on the surface of an agarose gel containing ethidium bromide (EtBr) and the ultraviolet-induced low-light fluorescence emitted by EtBr molecules intercalated into the DNA is evaluated. The high sensitivity and reproducibility of this quantitative method has been obtained using an advanced analysis system capable of distinguishing low-light fluorescent patterns, as in the case of DNA stained with EtBr, from the background. Use of an internal standard is necessary because the intensity of the signal is due to the aperture of camera diaphragm and to gel conditions. Using this two-dimensional analysis system it is possible to obtain rapid and precise quantitation of as little as 2ng of DNA.     

A non-destructive method for identifying the sex of ant larvae

The differences between adult male and female ants are often striking and obvious, yet both sexes appear virtually identical at the larval stage. Current methods for determining larval sex rely on genetic analyses or histology, both of which require killing all larvae examined. Here, we describe a method for identifying larval sex in vivo based on visible differences in genital imaginal discs. Using a light microscope, clear differences in genital disc morphology were observed between male and female larvae of the ponerine ant Harpegnathos saltator. Next, we investigated whether this technique could be broadly applied within ants and found similar differences in genital discs between male and female larvae of Aphaenogaster cockerelli and Camponotus floridanus. Taken together, our results show that genital discs can be used as a reliable indicator of larval sex in species from at least three major ant subfamilies. This technique should facilitate research into topics where information about larval sex is required.     

A simple method for the collection of Necator americanus larvae

A simple method for the collection of third-stage larvae of Necator americanus has been described. This technique provides repeated recovery of very clean larvae from cultures in moderate numbers.     

A sensitive method for measuring oxygen consumption

A technique is presented whereby oxygen consumption rates of the order of 10⁻⁶ μl/hr can be measured, thus providing a means for studying the respiration rates of single cells, even slowly respiring ones. The technique is based on the principle of incubating cells in extremely small chambers containing highly concentrated hemoglobin solutions. The absorbance shift occurring when hemoglobin is transformed from its oxygenated to its deoxygenated form is recorded microspectrophotometrically. The results obtained by this technique seem to be well in accordance with those of the Warburg manometric method. The technique is convenient and easy to handle and the sensitivity can be varied within wide limits, permitting different types of materials to be studied. In experiments using yeast cells, respiration rates from 1.0 × 10⁻⁶ to 1.8 × 10⁻⁶ μl O₂/cell/hr were revealed.     

A quantitative method for measuring protein phosphorylation

We have developed a novel method for quantitating protein phosphorylation by a variety of protein kinases. It can be used with purified kinases and their substrates in vitro or in combination with cell extracts. The method is based on the knowledge that protein kinase C (PKC) adds three phosphates to each molecule of its preferred substrate, myelin basic protein (MBP). A time course is performed in which a kinase is allowed to phosphorylate its preferred substrate or the protein under investigation in the presence of [gamma-32P]ATP. At the same time PKC is allowed to fully phosphorylate MBP. After resolving the products by SDS-PAGE, electrophoretic transfer, and determining the degree of incorporation of 32P by phosphorImager analysis, the data are converted to moles phosphate/mole protein by normalization with phosphorylated MBP. The method is both sensitive and relatively rapid and all the steps are commonly available in the biochemistry laboratory. We have used this method to confirm and extend information on the relationship of MEK1 and MAPK/Erk2 in rat lung fibroblasts exposed to V(2)O(5). A 4-h exposure to V(2)O(5) results in partial phosphorylation of MAPK/Erk2 such that 25% of the potential phosphorylation sites are occupied. We also demonstrate that despite multiple potential phosphorylation sites, recombinant human AP endonuclease is weakly phosphorylated in vitro (4% at best) by PKC, cGMP-dependent protein kinase, casein kinase II, and casein kinase I and not at all phosphorylated by MAPK. Furthermore we are unable to demonstrate phosphorylation in cell extracts from HeLa cells, mouse fibroblasts after oxidative damage with H(2)O(2) or alkylation damage with methylmethane sulfonate, or rat lung fibroblasts after oxidative damage with V(2)O(5).     

A novel method for measuring the thermal conductivity of organisms

Based on the theories of tissue optics and artificial neural network, the relationship between the optical properties and biological parameters was studied, and a new experimental method was derived. The properties of the organism were obtained indirectly by a black-box model derived by self-study of the artificial neural network between optical parameters and thermo-physical properties without using the heat transfer equation. In this method, the energy of light in diffuse radiation, diffuse transmission and collimated transmission was absorbed by a dual-integrating sphere experimental system of a spectrometer, and the spectrogram of the energy was obtained. Combining these spectral data of the energy, the diffuse-reflecting power, the diffuse transmissivity and the collimated transmissivity were calculated. The calculated results were taken as the input parameters of a black-box model. The experimental results show that there are apparent differences between the spectrogram of the energy on the diffuse radiation, the diffuse transmission and the collimated transmission of different matters, while there is a little difference in the same matter. Each spectrogram has its own characteristic. The values of the four thermal properties including the density, the constant pressure specific heat, the thermal diffusivity and the viscosity were calculated using the black-box model. Compared with the real values the calculated one has an average relative error between −5% and 5%. The conductivity of the tongue is 0.68 W/(m K) that calculated from the value of the density, the constant pressure specific heat and the thermal diffusivity. The results also show that there is a little difference on the conductivities in the longitudinal cross-section and the transverse section, but the effect of temperature on the conductivity of the tongue is not apparent. The difference implies the anisotropy of the properties of the organism, which cannot be easily obtained by a conventional experimental method.     

A colorimetric method for measuring the esterolytic activity of elastase

This paper describes a new colorimetric method for measuring the activity of elastase. The substrate used is acetyl-l-alanyl-l-alanyl-l-alanine-methyl ester. Its concentration is determined before and after enzymatic action by the hydroxamic acid method of Hestrin. The procedure described is simpler and more rapid than the usual potentiometric method and may be adapted to serial assays. With a 1-hr test, elastase concentrations as low as 0.2 μg/ml may be assessed accurately.     

Swimming performance in early development and the "other" consequences of egg size for ciliated planktonic larvae

The evolutionary significance of egg size in marine invertebrates is commonly perceived in energetic terms. Embryonic size should also have direct effects upon the forces that govern swimming, a behavior common to early larval development in the plankton. If swimming is ecologically important, early larvae may need to perform to a certain "standard", or threshold of speed and/or stability. The existence of performance standards in early development could therefore act to constrain the evolution of egg size and the evolution of development. Here we present the key parameters that characterize the upward swimming speed of ciliated spheroidal larvae moving at very low Reynolds numbers. The dependence of maximum supported mass upon larval size, and the independence of neutral-weight swimming speed from size, lead to hypotheses about scaling of swimming speed with size. Experimental studies with thirteen broadcast-spawning planktotrophs demonstrate that free-living embryonic swimmers in all of these species conform to a strong negative scaling of density with size that offsets increases in mass with increasing size. This trend suggests that swimming ability is broadly under selection in early development. In experimental studies and in a hydrodynamic model of larval swimming, the performance of trochophore larvae provides support for our hypothesized scaling relationships, and also for the concept of a standard in swimming speed. Echinoid blastulae, however, show relationships between speed and size that are not predicted by our scaling arguments. Results for echinoids suggest that differences in ciliary tip speed, or possibly in spatial density of cilia over the blastula's surface, result in significant differences in species' performance. Strong phyletic differences in the initial patterning and growth of structures used for swimming thus appear to cause significant differences in the relationship of swimming ability with embryo size.     

A technique for measuring the susceptibility of wheat bulb fly larvae to insecticides in the laboratory

A simple assay is described for measuring the toxicity of insecticides to larvae of wheat bulb fly (Delia coarctata) in the laboratory. The method should be suitable for other small soil insect larvae that cannot be obtained in large numbers and are difficult to treat and confine. A limitation of the technique is that it works only with insecticides that are soluble enough to be toxic in aqueous solution.     

A roentgenographic method for measuring nasal mucous velocity

Nasal mucous velocity was estimated by following the motion of radiopaque discs of Teflon by means of a fluoroscopic image intensifier. From 5 to 10 discs were deposited on the superior surface of the inferior turbinate with a forceps. No local anesthesia was employed and the subjects experienced no discomfort. The linear velocity of the discs was obtained by playing the videotape onto a television monitor, measuring distance with a ruler, and dividing by elapsed time. Duplicate runs of 1-2 min, 15 min apart were very reproducible but runs at 4-h intervals or daily over a 5-day period had a coefficient of variation of 30%. Average nasal velocity for individual ranged from 0 to 22.5 mm/min and group means ranged from 6. 8 to 10.8 mm/min. There was no statistically significant difference in nasal mucous velocity between young and elderly subjects nor was there a sexual difference. The saccharin test of nasal mucous transport was unsatisfactory because of inability to repeat the test more often than 1-2 h and its propensity to produce mild discomfort in a significant number of subjects. Saccharin times did not correlate significantly with values of nasal mucous velocity.