Meiotic gynogenesis affects the individual and gonadal development in sterlet Acipenser ruthenus

Larval growth and gonadal differentiation of gynogenetic sterlet Acipenser ruthenus were studied. The gynogenetic fish were produced by activation of albino sterlet eggs with UV‐irradiated sperm (collected from healthy coloration specimens), following by a heat shock of 34°C. Embryos were reared at 18.0 ± 0.5°C in a recirculation system and initially fed with Artemia sp. for 4 weeks and then fed with formulated feed. During the experiment, the length and weight of fish were recorded for the gynogenetic and control groups. Additionally, the analysis of gonadal sex differentiation was conducted with a 2‐week interval at 289, 303, 317, 331, 345 and 373 DPH. The mean body weight of the control group was significantly higher (p < .05) than the gynogenetic group only at 345 and 373 DPH, while the mean total body length was significantly higher at 331 and 345 DPH (p < .05). The gonad investigation was started at 289 DPH, and ~80% of females were found in the gynogenetic group during the trial period while the number of females and males was similar at 303, 331 and 373 DPH in the control group. The first symptoms of morphological differentiation appeared at 289 DPH, and the final shaping macroscopic structure of the gonad took place earlier in females than in males.     

Washing agents from sewage sludge: efficiency of Cd removal from highly contaminated soils and effect on soil organic balance

Purpose

To compare Cd removal from different soils with three washing agents recovered from sewage sludge (dissolved organic matter (DOM), soluble humic-like substances (HLS), soluble humic substances (SHS)). Also, to investigate how washing with these agents changes soil organic-matter composition (OM).

Materials and methods

Sandy clay loam (S1) and clay (S2) highly contaminated with Cd (300 mg kg^?1) were washed with DOM, HLS, or SHS solutions at various pHs, and with various washing times and washing modes (single or double). Cd distribution and OM composition were determined (including content of humic substances (HS), fulvic fraction (FF), labile humic acids (L-HA), and stable humic acids (S-HA)).

Results and discussion

Cd removal proceeded with pseudo-second-order kinetics. Equilibrium was reached in 30 min (S1) and 60 min (S2). DOM, HLS, and SHS removed 75–82% of Cd from S1, and 80–87% from S2. The most mobile fraction of Cd was removed after one wash. S2 retained more OM, including HS, than S1. Although washing did not change the HA/FF ratio in most variants, washing with DOM and HLS increased the percentage of L-HA in both soils. Washing with SHS increased S-HA content in both soils, but the percent content of S-HA was similar to that in the unwashed soil.

Conclusions

DOM, HLS, and SHS derived from sewage sludge can effectively remediate clay and sandy clay soils highly contaminated with Cd. Washing with an SHS solution can increase the content of the most stable carbon forms (HA), which is beneficial for carbon sequestration in remediated soils.

     

Determination of cytogenetic markers for biological monitoring in coypu (Myocastor coypu)

Cytogenetic tests are used to assess the influence of physical and chemical factors with potential mutagenic and genotoxic properties on the animal organism. The test results make it possible to eliminate mutagens, as well as helping predict possible genetic consequences in animal cells and assess animal resistance. The aim of this study was to examine, using cytogenetic tests, the spontaneous chromosome and DNA damage in coypu lymphocytes. Four tests: fragile site (FS), bleomycin (BLM), micronucleus, (MN) and comet were used for the first time in coypu cells. The averages with standard deviations obtained in the research were as follows: 3.30 ± 0.80 fragile sites/cell; 0.63 ± 0.80 BLM damage/cell; 6.10 ± 0.53% binucleated cells with MN; and 3.24 ± 0.63% DNA in tail. The present analysis showed high interindividual variation in spontaneous chromosomal and DNA damage levels. In the case of micronucleus, fragile sites, and comet assays, the differences between animals were statistically significant. The data suggest that these assays are sensitive enough to detect some effects on an individual animal and can be proposed as tools for coypu biomonitoring.     

Evaluation of sperm morphometry of rabbits (Oryctolagus cuniculus f. domesticus)

Sperm morphology and morphometry are considered parameters in fertility diagnosis. They are especially important in the case of species for which there is no standard with respect to morphometric sperm parameters. It is then crucial to apply the staining technique that has the least influence on the sperm structure and provides the most detailed image, so as to enable measurements. The aim of the research was to assess the morphometric parameters of rabbit sperm using silver nitrate staining. The staining process revealed a detailed image of the spermatozoon head and tail, thus enabling precise measurements. From these basic morphometric parameters, four additional shape indices characterizing the sperm head were calculated: ellipticity, elongation, roughness and regularity. These parameters more precisely characterize the shape of the sperm head. Silver nitrate staining can be used as an independent technique in assessment of sperm structure or to supplement routine diagnostics.     

Managing the Florida Everglades: Changing values, changing policies

The Florida Everglades is a ecologically rich land and water environment that has gone through three phases. In the first phase, a small indigenous population drew its low-impact livelihood from the Everglades. During the second phase, the Everglades was drained, plowed, developed, and seriously damaged, while helping to support a booming South Florida economy. During the third phase, earlier alterations of water flow patterns in a part of the original Everglades are being restored and agricultural impacts are being mitigated.     

Cover cropping influences physico-chemical soil properties under direct drilling soybean

In seeking effective methods to prevent soil degradation, conservation tillage plays an important protective role. Apart from significantly reducing production costs, cover crops contributes to beneficial changes in the soil environment. A three-year field experiment included three cover crops (winter rye, winter oilseed rape, and white mustard) subjected to mulching or desiccation and to the action of a herbicide at three rates (100%, 75%, and 50%). The study evaluated soil moisture and the content of organic matter, phosphorus, potassium, and magnesium in two soil layers (0–15?cm and 15–30?cm). Cover cropping had a positive effect on soil organic matter content. More organic matter (by 4.7%) was recorded in the topsoil layer (0–15?cm). Among the cover crops most favorable effect on the content of organic matter in the soil had white mustard (an increase of 14.2%) compared to the control. Moreover, rye and white mustard mulch increased the soil content of phosphorus and magnesium, while oilseed rape mulch increased the potassium content. At the critical growth stages (the flowering/pod set) of soybean (Glycine max (L.) Merril), soil moisture was dependent on mulching treatment and soil layers.     

Oak natural regeneration and conversion processes in mixed Scots pine stands

The main task of the study was to find out if spontaneous oakregeneration can play an important role in conversion processesof mixed Scots pine stands to native broadleaved forests. Thepaper examines the amount and structure of oak natural regenerationunder different gap sizes and defines the optimal gap size forinitiation, growth and development of oak regeneration. Theinvestigation was conducted in managed forests in the GarwolinForest District in the central part of Poland. All gaps, definedas openings in the canopy     

Drought in the forest breaks plant–fungi interactions

European Journal of Forest Research - Drought in the forest is not only a prolonged state of water shortage, but also an occasion where interactions between plants and fungi are affected. Water...