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The photoperiodism and hibernation
Pařezová, Lucie ; Bendová, Zdeňka (advisor) ; Weissová, Kamila (referee)
Many organisms living in seasonal environments use annual changes in the length of the day for timing of their responses, such as reproduction, migration or hibernation. Hibernation allows animals to survive difficult periods associated particularly with cold temperatures and lack of food resources. This adaptation requires many physiological, morphological and behavioral changes. Some of these changes take longer, so their right timing is crucial. For most hibernators in temperate regions shortening of the photoperiod is the most reliable signal for initiation of these changes. This work describes the transduction of photoperiodic information to the melatonin signal, its effects in the pars tuberalis and the significance of this structure in seasonal physiology. A more detailed description is devoted to hibernation, and in the last chapter there is briefly mentioned photoperiodism in nonhibernating organisms. Powered by TCPDF (www.tcpdf.org)
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Optimalization of photostimulation technology for delay sexual maturity of brook trout (Salvenilus fontinalis)
JUNG, Jakub
The aim of the present work, based on two experiments, was to evaluate the impact of photostimulation as a prevention for delaying the sexual maturation of brook trout (Salvenilus fontinalis). Another additional experiment was to describe which effect has photostimulation on the consequences of aggressive behaviour of males. Two experimental groups were established and differed in illumination sources: the metal halide lamps (HAL) and the light emitting diodes (LED). The photostimulation timing (photoperiod) was tested in following experiment. In both tested groups (HAL and LED) the photoperiod was prolonged to 18L:6D in comparison to the control group with natural photoperiod. The results shows that before spawning females and males in both tested groups (HAL and LED) reached significantly higher body weight up to 100 g (=0.05) due to desirable delayed sexual maturation (up to one month). By obtaining the same results in both groups, clearly profitable source of illumination was LED and the time for sufficient application before spawning was 67 days. Moreover photostimulation had also positively reflected in the elimination of aggressive behaviour of males. The results of the present study suggest that photostimulation may be applicable in the intensive culture systems of salmonids in the Czech Republic.
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Vliv délky světelného dne na příjem krmiva a růst síha peledě (Coregonus peled) v intenzivním chovu
KOS, Martin
The effect of the length of the daylight on growth of in peled (Coregonus peled) juveniles was tested in the intensive culture. Fish of mean body weight 1.82 +- 0.48 g and total length of 65 +- 7 mm were divided into four groups (the ratio of light and darkness 12k12, 16k8, 20k4, 24k0). The experiment lasted for sixty-three days. Every twenty-one days fishes were sampled for biometric measurements. Fish reached mean body weight of 15 +- 4.9 g (12k12); 15.6 +- 4.5 g (16k8); 16.7 +- 4.5 g (20k4); 16.8 +- 5 g (24k0) in experimental groups. The longest total body length was detected in both 20k4 and 24k0 groups (127 +- 11 mm). The lowest one was registered in the 16k8 (114 +- 11 mm). The highest condition coefficient had group 16k8 and lowest was found out in group 20k4. Specific growth rate during the course of the experiment was 3.33 %xday -1 (12k12); 3.28 %xday -1 (16k8); 3.49 %xday -1 (20k4) and 3.43 % xday -1 (24k0). The highest final survival (95.8 +- 1.4 %) was achieved in group 12k12. On the contrary, group 16k8 showed lowest survival of 90.0 +- 4.6 %. There were no significant differences in final survival rate.
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CIRCADIAN GENES AND REGULATION OF DIAPAUSE IN INSECT
BAJGAR, Adam
This thesis considers various roles of circadian clock genes in insect physiology. Application of molecular-biology methods in Pyrrhocoris apterus, non-model insect species, enable us to investigate involvement of circadian clock genes in photoperiod induced physiological responses. We discover involvement of neuroendocrine cells, and a role of Juvenile hormone (JH) signalization in transduction of photoperiodic signalization to peripheral tissues. We found new principles of JH signal diversification in tissue specific manner, and in addition described molecular mechanism of photoperiod induced changes in gut physiology. Comparison of gut and fat body tissue reveals that mechanism observed in the gut is tissue specific, and that circadian clock genes exhibit tissue specific functional pleiotropic effect.
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The influence of photoperiod on the egg production of phasmid \kur{Peruphasma schultei}.
TOCHOROVÁ, Pavla
The aim is to determine the importance of photoperiod for oviposition of Peruphasma schultei. The theoretical part covers common description of the reproduction and embryonic development of phasmid. Included the climatic factors affecting physiological action and brief description of the biological clock of insects. Experimental individuals were are kept in three different photoperiods with constant temperature of 25 °C. Control and collection of eggs ran at intervals of two hours. It was shown the influence of photoperiod, time and their interaction on the number of eggs and imposed the difference in putting across time.
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Effect of selected abiotic factors on wing polymorphism of semiaquatic bug Microvelia reticulata Burmeister, 1835.
ČERMÁKOVÁ, Táňa
Wing polymorphism of semiaquatic bugs is affected by environmental factors as temperature, photoperiod, population density or permanency of habitat. The heritability has its own specific part, too. A lot of field studies suggest that crucial effect on wing polymorphism has temperature, but laboratory experiments often do not confirm this hypothesis. The main aim of this thesis was to describe the effect of environmental factors (photoperiod, temperature and permanency of habitat) on wing polymorphism of Microvelia reticulata, additionally of Gerris lacustris. The partial tasks included description of effect of mentioned abiotic factors on mortality and rate of development. The individuals of both species were kept at combinations of two levels of temperature, photoperiod and permanency of habitat (overall at eight treatments) from first larval instar to adult. All adults of Microvelia reticulata emerged as apterous, so there was no response of wing polymorphism to tested environmental factors. The main influence of heritability is presumable. Only ten individuals of G. lacustris developed into the adult stage, so it was impossible to describe the influence of abiotic factors on wing polymorphism, mortality and lenght of development in this species. Mortality of individuals of M. reticulata was significantly influenced by the type of substrate. Only 3.5% of individuals survived when reared on wet filter paper, while 80.5% on the water surface. Both other factors (temperature, photoperiod) had no effect on total mortality. There was no difference between mortality of males and females, so it is impossible to note sexual dependent mortality. The lenght of development did not differ between sexes either. Lenght of development was significantly affected by temperature, as low temperature reduces development of M. reticulata. The fastest development showed nymphs of second instar and slowest development nymphs of fifth instar at all treatments. Since the effect of abiotic factors on wing polymorphism was not found in M. reticulata, it would be sufficient to study the effect of heritability on development of wings in this species in the future.
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