Dynamics of ammonia excretion in juvenile common tench, Tinca tinca (L.), during intensive rearing under controlled conditions

This paper presents the first data on ammonia excretion by fed and starved juvenile common tench. The aim of the study was to determine the amount of ammonia excretion by juvenile common tench Tinca tinca (L.), fed with a commercial feed under intensive rearing conditions. Rearing was conducted for a period of 4 weeks at a water temperature of 27 °C. On the test day, the amounts of ammonia excreted by starved fish (over 12 h: control group) and fish fed with a morning feed dose (3 % of biomass: experimental group) were determined at 1, 3, 5, 7, 9 and 11 h after feeding. Ammonia excretion measurements were taken in 7-day intervals. Despite the increased growth rate in successive weeks of experiment, the amount of ammonia excreted by the fish was always at a similar level within the control (maximum 0.26 mg g^?1) and the experimental group (maximum 0.39 mg g^?1). This paper presents for the first time reliable amount of ammonia excreted by fed and starved juvenile common tench. The obtained results may also increase the effectiveness of intensive rearing procedures (taking into account stocking density and feeding regime) and allow to design the most effective biofiltration capacity of recirculating aquaculture systems for the commercial production of this species.     

The parameters of energetic status of the wild Atlantic salmon (Salmo salar L.) spermatozoa

The energetic status of fresh sperm of wild Atlantic salmon (Salmo salar L.) was presented in selected males (n=10) with motility rate ≥80%. Purine and pyridine nucleotides: adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), guanosine triphosphate, guanosine diphosphate, guanosine monophosphate, inosine monophosphate, nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate; nucleosides: adenosine, guanosine and inosine; bases: hypoxanthine, xanthine and uric acid were determined using the high‐performance liquid chromatography method. The average value of adenylate energy charge in the group was 0.77 ± 0.10, and the mean total adenine nucleotide content (TAN) was 65.1 ± 18.3 pmol × 10^?6 spermatozoa. The mean concentrations of ATP, ADP and AMP were 43.5, 11.8 and 9.9 pmol × 10^?6 spermatozoa respectively. The concentrations of the other energetic nucleotides studied were lower. In all males studied (n=23) with a motility rate from 0% to 95%, no statistically significant correlation between the per cent of motile sperm and ATP concentration was found (R_s=0.35), whereas the correlation between the per cent of motile sperm and ADP was statistically significant (R_s=0.60). A negative correlation was found between hypoxanthine and the per cent of motile spermatozoa (R_s=?0.44). Our results suggest that hypoxanthine is the final product of salmon spermatozoa of adenine nucleotide catabolism.     

Food selection of burbot (Lota lota L.) larvae reared in illuminated net cages in mesotrophic Lake Maróz (north-eastern Poland)

Feeding and food selection of burbot (Lota lota L.) larvae reared in illuminated cages were studied. The experiment was carried out in mesotrophic Lake Maróz, in north-eastern Poland, for 6 weeks in two successive years. The initial stocking density was 1,250 larvae (20 DPH) per cage. Food selection according to the zooplankton groups (Rotifera, Cladocera and Copepoda) and length classes was expressed by the Strauss linear selectivity index (L). Zooplankton species composition in the lake was similar in the two seasons of the study and organisms shorter than 0.5 mm prevailed in the plankton. The mean number of prey found in burbot alimentary tracts increased from about 40 up to over 200 during the course of the study. A very large inter-individual variation in the amount of food organisms consumed by fish was noted. Analysis of the values of the Strauss food selectivity index shows that at the beginning of the first year of the experiment, burbot larvae preferred copepods, most numerous in the environment at that time; later, fish tended to select cladocerans. In the second year of the study, fish more often ate copepods, irrespective of their quantities in the environment. During the whole study, reared burbot larvae did not eat rotifers, even when they were numerous in cages. Similarly to the rotifers, the smallest planktonic organisms, measuring up to 0.5 mm in length, were typically neglected by fish, while the 0.6–1.0 mm group was most frequently selected. There were also considerable individual differences between particular burbot specimens in their food preferences.     

Phosphorus sources for winter oilseed rape (Brassica napus L.) during reproductive growth – magnesium sulfate management impact on P use efficiency

It has been assumed that phosphorus (P) resources accumulated in vegetative tissues of winter oilseed rape (WOSR) at flowering are too low to cover the requirements for the high-yielding crop during the seed filling period (SFP). The data used originated from field experiments with nutrients sequentially added to WOSR, using crops grown on soil rich in available P (2008–2010). The low-seed density canopies during SFP resulted only from the P remobilized from the pre-flowering crop resources. The high-seed density canopies depended on both P remobilized and its uptake from soil (PFPU). The maximum PFPU of 30.7 kg P ha^?1, and the concomitant seed density of 86.8 ? 10³ m^?2, resulted in a maximum seed yield of 5.8 t ha^?1. Internal P resources were reused during SFP irrespective of the initial P content and without impact on phosphorus use efficiency (PUE). The study showed that PUE improvement in WOSR is related to the seed density of primary branches. Its development depended on the supply of potassium, magnesium and sulfate. A PUE of 105.4 kg seed kg^?1 P was used to predict the seed yield gap (PYG). This index can be used as a measure of P management efficiency in WOSR canopy.     

Subcelullar localization of proteins associated with <Emphasis Type="Italic">Prune dwarf virus</Emphasis> replication

The fungus Colletotrichum lindemuthianum is the causal agent of anthracnose, one of the most severe diseases of the common bean (Phaseolus vulgaris). The infection process begins with the adhesion of conidia to the plant’s surface. Appressoria are then formed, allowing penetration of the fungus. Next, the biotrophic phase begins, followed by the necrotrophic phase. Due to the peculiar nutrition mode of the fungus, including both of the previously mentioned stages, it is of great interest to determine which genes are involved in the transition between the two phases during the infection process. To determine this, suppression subtractive hybridization (SSH) was used in association with qRT-PCR in the present study. These methods allowed for the identification of genes that were differentially expressed at each developmental stage of the fungus in the plant. This is the first report on the use of the cited techniques to evaluate the infectious cycle of the fungus. A total of 175 sequences exhibited significant identity (e?≤?10^?5) with sequences present in the sequenced genomes of P. vulgaris and C. lindemuthianum; approximately 41 % of those were determined to belong to the fungus, and 59 % were determined to belong to the plant. Of the predicted sequences, 68 % were of unknown function or were not found in the databases. Among the analyzed expressed sequence tags (ESTs), sequences were found that encode proteins related to: primary and secondary metabolism; the transport of different compounds; the degradation/modification of proteins; cell regulation and signaling; cellular stress response; and the degradation of exogenous compounds. The obtained results allowed for the identification of sequences encoding proteins that are essential for the progression of anthracnose. Furthermore, it was possible to identify new genes, the functions of which have not yet been described, and even to identify unique genes of C. lindemuthianum that are involved in the pathogenicity and virulence of this fungus.     

Influence of Insolation on the Efficiency of NO<Subscript>3</Subscript> Removal from Wastewater Treated in the Hydroponic System

The use of plants and natural processes for wastewater treatment is an issue that arouses interest among technologists and scientists around the world. The aim of the article was to analyze the influence of the air temperature and insolation on the removal of nitrate nitrogen from the wastewater treated in the hydroponic system, under greenhouse conditions. Samples of sewage for its quality tests were taken from a wastewater treatment plant (WWTP) located in the southwestern part of Poland. Data regarding daily sunshine duration and average daily air temperature values in selected periods of 2013–2016 come from a meteorological station located 30 km from WWTP. The conducted research and analyses of the results clearly indicate that under moderate climate conditions, the amount of solar radiation reaching the Earth’s surface is insufficient to ensure the year-round, effective wastewater treatment process in the hydroponic system. In the case of air temperature, no correlation was found between the tested parameters, which indicates the lack of temperature influence on the efficiency of NO₃ removal from the wastewater by macrophytes growing in the lagoon.     

Length of winter coat in horses depending on husbandry conditions

This paper analyzes changes in the length of coat on selected body areas in horses and ponies kept under different husbandry (stable) conditions during the winter‐spring period. The study included 12 Ma?polski geldings and 12 geldings of Felin ponies aged 10–15 years. Horses were kept in two stables (six horses and six ponies in each stable). The type of performance, husbandry conditions and feeding of the studied animals were comparable. As of December 1, samples of hair coat from the scapula, sternum, back and abdomen areas of both body sides were collected seven times. The lengths of 20 randomly selected hair fibers were measured. Daily measurements of air temperature in the stables were also taken. An analysis of variance (ANOVA) was performed using the following factors: the body part from where the coat was sampled, the subsequent examination and the stable as well as the interaction between these factors. The significance of differences between means was determined with a t‐Tukey test. The relations between air temperature in the stable and hair length were calculated using Pearson's correlation. It was found that air temperature in the stable impacts the length of winter coat in horses and ponies. The effect of this factor is more pronounced in ponies; as in the stables with lower temperatures it produces a longer hair coat which is more evenly distributed over the body in comparison with horses. Keeping horses and ponies in stables with a low air temperature accelerates coat shedding by approximately 25 days. Coat shedding begins from the scapula area.     

Analysis of Granulometric Composition of Algal Suspensions in Wastewater Treated with Hydroponic Method

The aim of the study was to determine the changes in suspension particle size identified in biologically treated wastewater, which was then treated in hydroponic system with use of engineering lighting by the light-emitting diodes (LED). The study was subjected to wastewater purified under laboratory conditions, in a hydroponic system using the effect of macrophytes Pistia stratiotes and growing algae. Measurement of particle size was made using a laser granulometer. Analysis of the results showed that the additional lighting of the hydroponic system with LED can significantly influence the ability of the suspension particles to agglomerate and, consequently, determine their sedimentation properties. In hydroponic system supported by additional lighting, more particles were observed with equivalent diameter D(3.2) smaller than 10 μm than those in the tank without additional lighting, indicating a higher reactivity of the particles. Determining the size of equivalent diameters D(4.3) allowed us to observe that in hydroponic system, particles of relatively small size predominate, which negatively affects the sedimentation process of the suspensions. Determination of particle size of suspensions consisting mainly of algae and the dynamics of their changes are the basis for specification of an effective method of removing particles from the system to protect the receiver from excessive suspension concentrations.