Molecular cloning of gonadotropin cDNA in sevenband grouper, Epinephelus septemfasciatus

The cDNA for glycoprotein hormone (GPH) α-subunit, β-subunits of the FSH (GtH I) and LH (GtH II) were isolated, cloned, and sequenced from sevenband grouper pituitary using RACE PCR. These results show that sevenband grouper has two different types of gonadotropins FSH (GtH I) and LH (GtH II), as other teleosts.     

The Impact of Multiple Freeze–Thaw Cycles on the Microstructure of Aggregates from a Soddy-Podzolic Soil: A Microtomographic Analysis

With the help of computed X-ray microtomography with a resolution of 2.75 μm, changes in the microstructure and pore space of aggregates of 3 mm in diameter from the virgin soddy-podzolic soil (Glossic Retisol (Loamic)) in the air-dry, capillary-moistened, and frozen states after five freeze–thaw cycles were studied in a laboratory experiment. The freezing of the samples was performed at their capillary moistening. It was shown that capillary moistening of initially air-dry samples from the humus (AY), eluvial (EL), and illuvial (BT1) horizons at room temperature resulted in the development of the platy, fine vesicular, and angular blocky microstructure, respectively. The total volume of tomographically visible pores >10 μm increased by 1.3, 2.2, and 3.4 times, respectively. After freeze–thaw cycles, frozen aggregates partly preserved the structural arrangement formed during the capillary moistening. At the same time, in the frozen aggregate from the AY horizon, the total tomographic porosity decreased to the initial level of the air-dry soil. In the frozen aggregate from the EL horizon, large vesicular pores were formed, owing to which the total pore volume retained its increased values. The resistance of aggregate shape to the action of freeze–thaw cycles differed. The aggregate from the EL horizon completely lost its original configuration by the end of the experiment. The aggregate from the AY horizon displayed definite features of sagging after five freeze–thaw cycles, whereas the aggregate from the BT1 horizon preserved its original configuration.     

Changes in the pore space of soil constructions in physical laboratory models

The dynamics of pore space structure in different filled soil constructions during water infiltration and wetting–drying processes is studied. Model laboratory experiments in columns physically simulate water infiltration after penetration at a rate of 600 mm with free outflow from the lower end of the column followed by multiple drying of soil constructions composed by alternating layers of sand, peat, and A and В horizons of soddy-podzolic soil. In two- and three-dimensional tomographic images, changes in the pore space and the interpenetration of solid phase at the boundaries between individual horizons of soil constructions are analyzed.     

Organizing the ecological monitoring of soils as a constituent part of the state land monitoring and its first results (using the example of Orenburg oblast)

This paper suggests the model for organizing the soil control within the framework of state ecological land monitoring carried out in Russia. Methodical approaches to forming the network of observation areas are expounded. The first results speak for the significant differently directed changes in the properties of soils in Orenburg oblast for the last several decades that are related with erosive processes and transformation of the main physical properties and organic matter.     

Formation of Vesicular Pores in Aggregates from the Eluvial Horizon of Albic Glossic Retisol during Freeze-Thaw Cycles

Eurasian Soil Science - In this article, we discuss the contribution of capillary wetting and multiple freezing and thawing to the formation and evolution of vesicular micro– and mesoporosity...     

Soil hydrology: Stages of development,current state,and nearest prospects

The main stages of the development of soil hydrology are described. These are: (1) the stage of classical hydrology based on the concepts of soil water forms and soil hydrological constants; (2) the stage of thermodynamic approaches toward assessing the statics and dynamics of soil water (soil hydrophysics); and (3) the modern stage of diverse approaches taking into account the specificity of water movement in a heterogeneous pore space (the development of preferential water flows), the specificity of the hydrological properties of soils in dependence on the scale of their examination, and the impact of the living soil phase on the soil hydrological processes. The diversity of modern approaches toward soil hydrology is reflected in the names of new branches of this science, such as hydropedology, geohydrology, biohydrology, etc. At the modern stage, all the conceptual approaches typical of the earlier stages of the development of soil hydrology are also applied. At present, soil hydrology is an actively developing field of soil science with clearly understood limits of application, advantages, and disadvantages of the methods typical of the first two stages. On this basis, an integral quantitative multilevel concept of soil hydrology is being developed.     

The effect of organic matter on the difference between particle-size distribution data obtained by the sedimentometric and laser diffraction methods

Particle-size distribution in dispersed sediments, soils, atmospheric dust, and other natural objects is their fundamental characteristic. The methods of sedimentometry (the pipette method) and laser diffraction have been applied to study particle-size distribution in a typical chernozem of Kursk oblast from the Alekhin Central Chernozemic Reserve. The content of the clay fraction as determined by the method of laser diffraction is three to five times lower than the clay content determined by the traditional pipette method. One of the reasons for such a great difference in the results obtained by two different methods is related to the low density of the solid phase of the particles of soil organic matter that have the size corresponding to the fine and medium silt fractions. Owing to this, they fall into the category of the clay fraction during the traditional sedimentometric analysis. The initially water-stable aggregates of 0.25–0.5 mm in size are subjected to several stages of their breakdown under the impact of ultrasonic dispersion with the detachment of small particles from their surface layers. The remaining aggregates have different resistance to ultrasonic treatment. After the long-term ultrasonic dispersion, the most stable microaggregates still exist in the soil mass. These microaggregates may only be decomposed to elementary soil particles after the addition of sodium pyrophosphate.