National Repository of Grey Literature 509 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Molecular mechanisms of environmental sex determination in reptiles
Maslova, Mariia ; Kratochvíl, Lukáš (advisor) ; Krylov, Vladimír (referee)
Molecular mechanisms underlying environmental sex determination remained elusive for half a century, until just recently, when new insights into the topic were gained. The thesis summarizes current progress on this issue and focuses, among other things, on the role of oxidative stress and regulation of gene expression in the process of sex determination and sex reversal.
Water in physics and physics in water
Breburdová, H. (2022): Water in physics and physics in water. Diploma thesis. České Budějovice: University of South Bohemiain České Budějovice, Faculty of Education. This diploma thesis focuses on research-based teaching and the creation of physics experiments fit for teaching physics at the lower-secondary level of education. The primary goal of this thesis is to suggest certain physics experiments that, while allowing the use of water, also explain the basic behaviour of liquids in physics. Furthermore, it aims to create a worksheet for realised research-based. The outputs of this are selected experiments and a worksheet of research-based teaching.
Faktory ovlivňující excystaci žaludečních kryptosporidií přežvýkavců
In this study, we investigated the effects of temperature and pH on the excystation of gastric Cryptosporidium of mammals. Oocysts of Cryptosporiidum andersoni, obtained from a naturally infected cow, were used in this study. Oocyst viability was de termined by propidium iodide staining (PI). The first factor studied was temperature. Oocysts stored in dH2O were incubated in water bath preheated to temperatures between 32 and 44 °C for 5, 15, and 30 min. With increasing temperature and time, we observed a higher percentage of excysted oocysts. Most oocysts excysted at 40 °C and heating for 30 minutes. In addition, excystation of oocysts was also examined in solutions with different pH values (in a range of 29) heated in a water bath at 40 °C. The optimal pH for excysting is between 6 and 7; however, even at lower values, enough oocysts excyst to cause infection.
Comparison of different ways of breeding, nutrition and controlled reproduction of Lota lota
Based on the results reached after 216 days of experimentation with various breeding types, it can be said that the type of feed is not of paramount importance. This fact is based on the previous adaptation of submitted food, this is especially important for artificial feed. From our point of view, the more important factor is temperature, intensity and method of breeding. Prey selections choices involving 11 species of fish were performed on age groups of different burbot. All groups of burbot preferred the following species: grass carp, pikeperch, tench and stone moroko. The non-preferred species was ruffe. And different preferences were set for common carp, silver carp, burbot, sunfish and also for roach. The study evaluated reproductive parameters in burbot (Lota lota ) and focused on incubation time in two localities. Burbot spawning was observed from January to early February at an average temperature of 1.55 +- 0.9 °C in Borova Lada and 4.78 +- 0.11 °C in Mydlovary. For burbot at the age of 2+, at an average 1166 +- 100 were determined number of swollen eggs per gram. Relative fecundity was at 257260 +- 70678 eggs per kilogram of female. The absolute fecundity was at 24232 +- 6753 eggs.The last parameter evaluated was the incubation period. The average incubation period in the years 2020-2022 was 202 +- 24.55 °D in Mydlovary and 75.8 +- 16.67 °D in Borova Lada. In connection with artificial spawning, in this study, we further point out the possibility of peeling artificially spawn eggs with NaClO, in which we did not observe a negative effect.
Dynamika rozvoje včelstva ve Warré úlu
This bachelor's thesis deals with the dynamics of bee colony development in the Warré Hive. The Warré Hive aka the People's Hive can be easily made at home, it is undemanding to operate and it is used for natural beekeeping. The aim of this work was to compare the construction, thermal and humidity effects, which could influence the development of bee colony. The experiment was carried out from May to September, regular inspections were performed based on climatic conditions. The areas of sealed brood, eggs, larvae and bees were determined. Each beehive was equipped with a device recording temperature and humidity. The experiment station was located in Číhaň (Klatovy district) at 593 meters above see level. The measurement results differed. They did not demonstrate whether the beehive construction has an impact on the bee colony development. However, the results show that the beehive construction affects the internal climate of the beehive.
Rizikové faktory v kabině sklízecích mlátiček
The diploma thesis is focused on harvesting threshers in terms of noise, dust and temperature in the cab. The work is divided into two parts, theoretical and practical. In the theoretical part there are basic data and concepts of harvesters, acoustic materials and health protection at work in agriculture. In the practical part itself was performed measurement of noise, dust, temperature and humidity in the cabin cabin cabinet. Measurements took place on land of agricultural cooperatives and private owners. Based on the measured values, an overview of the parameters of individual machines was created.
Evaluation of qualitative and quantitative parameters of entomopathogenic fungus \kur{Beauveria bassiana} related to the inoculum production temperature
RYBAROVÁ, Kateřina
Bachelor thesis is focusing on the entomopathogenic fungus Beauveria bassiana strain GHA, which is contained in the commercial bioproduct Botanigard. Botanigard is a product used in biological control in many countries around the world to control a wide range of pests of various plant species. In this thesis, "in vitro" (radial growth, spore production) and "in vivo" parameters (virulence) of the GHA strain of Beauveria bassiana were tested at various temperatures on different nutrient media. The most optimal temperature for radial growth of the GHA strain was 25 °C, on media with a nitrogen to carbon ratio of 20:20. The GHA strain produced the largest amount of conidia on the medium with a nitrogen/carbon ratio of 20:40 at temperature 25 °C. On the contrary, the smallest conidia production was obtained on medium PDA and nitrogen/carbon medium in ratio 5:10. The temperature of 25 °C was also the most optimal for the infection of larvae of Tenebrio molitor. Thesis also deals with the comparison of blastospores production of GHA strain with other strains of B. bassiana isolated from different geographical areas. The strain isolated in Argentina had the highest production of blastospores on MEB medium.
Faktory ovplyvňujúce nástup pohlavnej dospelosti u rýb a možnosti skrátenia generačného intervalu - prehľadová štúdia
GARAYOVÁ, Margaréta
The aim of the this thesis was to develop a comprehensive overview study on the onset of sexual maturity, the factors that affect the onset and the possibilities of shortening of generation interval. Sexual maturity can be understood as a trait, resp. phenotypic expression, with individuals undergoing puberty before reaching adulthood. Puberty in fish is very important for farmers or breeders, as it affects a number of important parameters. The onset of puberty is influenced by many factors, either internal or external. Internal factors include fish species, genetic predisposition, health and fitness condition, the size and age of fish, sex of fish, and most importantly, the endocrine system. Based on the role of sex, we can state that in most species of fish in the Czech Republic and Slovakia, females mature later than males. The fact that individuals are sexually mature points out the functionality of the brain-pituitary-gonadal axis, which role is indispensable. GnRHs (gonadortropin-releasing hormones) or otherwise so-called hormone triggers with their effect on the pituitary gland and the secretion of LH (luteinizing hormone) and FSH (follicle-stimulating hormone), which further affect the gonads, are the center of this axis. Another gland with internal secretion that influences the onset of puberty is the pineal gland with the hormone melatonin. There are many external factors, but the thesis focuses on factors influencing the onset of sexual maturity of our fish and these are water temperature and photoperiod. From the obtained information, we can claim that in carp fish the key factor is the temperature, whereas in salmonid fish it is the photoperiod. For perch fish, this is still not clear. Taking into consideration carp fish, we can shorten the generation interval with a constant higher temperature. On the other hand, in the case of perch (Perca fluviatilis), we can achieve the shortening of the generation interval by shortening the photoperiod simultaneously with the decreasing of the temperature at the right time. Concerning a two-year old pikeperch (Sander lucioperca), we can achieve the same result at a temperature of 12 ° C for the period of three months. In the case of rainbow trout (Oncorhynchus mykiss), early maturation may be best achieved by continuous light in the spring followed by a sudden reduction of the photoperiod together with an increased temperature. In the case of atlantic salmon (Salmo salar), brook trout (Salvenilus fontinalis) and artic charr (Salvenilus alpinus), continuous fotoperiod causes a delay in puberty, however, the increased temperature has a stimulating effect on the onset of puberty for them, too. To sum up the gained information, I conclude that even though one factor may play a primary role on the maturation, other factors also have an impact, sometimes even significant. By manipulating with the above mentioned and other factors, we can achieve a shortening of the generation interval in our fish, which may be the goal of breeders in the Czech Republic and Slovakia.
Vliv teploty na oplozenost a líhnivost po krátkodobém skladování neoplozených jiker sumce velkého (Silurus glanis)
PŘIBYL, Tadeáš
The experiment validated the impact of storage of artificially spawned unfertilised eggs of European catfish on fertilization, hatching and the beginning of exogenous food intake throughout the transition from the embryonic to larval life period. The eggs from artificially spawned individuals have been used for this experiment using the induction of ovulation by the carp pituitary system. Sperm from each individual was collected by stripping using a hypodermic needle, that were partially filled with immobilising solution for sperm before artificial spawning of female individuals. Artificial stripping of fish was carried out under anaesthesia (by clove oil). Immediately after artificial hatching, samples of eggs (approximately 50 g) were put into six plastic bowls. Covered with wet cloth, bowls with eggs were placed into tempered, isolating thermo boxes with temperatures of 5, 10, 15, 20, 25 and 30 °C. Subsequently, in time intervals of 0,5, 1, 2, 3, 4, 6, 8 and 10 hours (after spawning) a small amount of eggs (approximately 50 pieces) was taken away from each temperature and put into glass beakers (with three repetitions), then the sperm was added and finally activated by adding water. In beakers with incubated non-sticking eggs and during the consequent storage of hatching embryos through temperature between 19,5-20 °C, water was changed two times a day. Approximately 4 hours after incubation, the exact number of used and fertilised eggs, was calculated. Unfertilised eggs (of white colour) and dead embryos were removed. Hatchery was assessed approximately 100 hours after fertilisation, when all living embryos had been hatched. After another 115 hours, throughout the transition from the embryonic to larval life development, live food (nauplia Artemia) was put into each bowl. Three hours after, individuals that began the food intake were calculated. The highest level of fertilisation was found in eggs stored between 0,5 and 2 hours (95,0?2,2 % - 100,0?0,0 %). The decrease in fertilisation is noticeable in all tested groups after 3 hours from stripping. Statistically significant decrease in fertilization was detected in eggs stored for 6 hours, the storage temperature did not affect the fertilization. Similar results have been maintained also in hatchery, where hatchery decreases as storage time increases. The highest level of hatchery was found in eggs stored in 25 °C (for 0,5 h 61,4?5,5 %), or more precisely 1 h 42,8?12,9 %). Hatching significantly decreases in all storage temperatures when storage time is longer than half an hour. The last parameter concerned how many percent of the individuals began the food intake. The highest level was recorded in eggs stored for half an hour (after spawning) in 25 °C (60,1?5,3 %), 30 °C (54,5?17,7 %) and 20 °C (39,0?12,7 %). On the contrary, storage temperatures 5 °C, 10 °C and 15 °C had results between 8,9?2,8 % and 35,0?18,8 %. Total mortality was detected when the storage time was more than 8 hours. It is necessary to fertilize the eggs as soon as possible (max. up to half an hour) after spawning, and to avoid storage of eggs at low temperatures (below 15 °C), to obtain viable individuals.
Vliv nasycení kyslíku ve vodě na efektivitu intenzivního chovu candáta obecného (Sander lucioperca) v recirkulačním akvakulturním systému
This thesis deals with an issue of Zander (Sander lucioperca) production in a recirculating aquaculture system RAS in different oxygen rates (50-80% O-, 80-110% Os and O+ 110-150%). Zander weighted W=22,98?15g was planted into two identical recirculating systems with different water temperature. SGR, FCR and FC of survival and general health condition of kept fish in hematology, biochemistry as well as stress indicators were evaluated. The results proved a negative influence of hypoxia (50-80%) on the food reception, growth and general survival of experimental fish kept in this environment in both the recirculating systems with water temperature 20 and 23°C. In the group O- kept in RAS 20°C, higher coefficient of FCR=1,11 was proved in comparison with group O (normoxia) and group O+ (hyperoxia), where no significant difference (p0,05) was recorded. The health condition showed a significant difference (p0,05) of O group in comparison with group O+ and O in RAS 20°C during the TBARS evaluation (brain, gills, muscle), assessing SOD in liver, and GPx (brain and muscle). By determining the HSI, SSI and VSI indexes, the significant differences (p0,05) of HSI and VSI for O+ and O groups in comparison with O- were proved.

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