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Nasl. z nasl. zaslona. Opis vira z dne 11. 7. 2023. Abstract. Bibliografija: str. 51-52.

V magistrski nalogi smo primerjali odzive filiformnih senzil stenice Pyrrhocoris apterus na zračni tok z različnimi časovno-prostorskimi lastnostmi. Izmerili smo amplitudo, hitrost in fazo odklona čutilnega laska ter fiziološki odziv (proženje živčnih impulzov) senzil T1 in T2 pri različnih amplitudah, frekvencah in smereh sinusnega toka. Izmerili smo tudi njihov odziv na naraven dražljaj, in sicer utripanje kril muhe, ki je potencialni parazit stenic. Ugotovili smo, da je senzila T1 bistveno bolj občutljiva na sinusni tok kot T2. Različni občutljivosti omogočata širše dinamično območje celotnega sistema. Sprememba smeri toka vpliva na fazo odklona čutilnega laska ter fazo in amplitudo fiziološkega odziva senzil. Velike razlike se pojavijo med senzilami na strani vira toka in senzilami na kontralateralni strani, manjše razlike pa tudi med ipsilateralnimi senzilami. Smerna odvisnost odziva torej kljub majhnemu številu senzil omogoča grobo kodiranje smeri dražljaja. Senzile T1 in T2 se odzovejo na muho na razdalji več kot 10 cm. Odzovejo se na nizko-frekvenčne tokove in na oscilacije zračnih delcev, ki imajo frekvenco utripa kril. Slednje izzovejo pri kontralateralnih senzilah T1 sinhrono proženje živčnih impulzov s frekvenco utripa kril. Stenica P. apterus torej lahko zazna potencialne plenilce/parazite, kot je muha, in jih morda na osnovi sinhronega proženja impulzov senzil celo prepozna. In this master thesis we compared the response of filiform sensilla of the firebug Pyrrhocoris apterus to airflow with different temporal and spatial properties. We measured the amplitude, speed and phase shift of the sensory hair deflection and physiological response (the firing of action potentials) of T1 and T2 sensilla at different amplitudes, frequencies and directions of sinusoidal airflow. We also measured their response to airflow produced by flapping wings of flies, which are potential heteropteran parasites. The T1 sensillum is significantly more sensitive to the sinusoidal air current than the T2 sensillum. Different sensitivity enables a wider dynamic range of the entire system. Changes in the direction of the airflow had an effect on the phase shift of the sensory hair and the phase and amplitude of the physiological response. Significant differences were observed between the sensilla on the source-side of airflow and the contralateral sensilla, minor differences were observed between the ipsilateral sensilla. The directional dependence of the response, despite the small number of sensilla, enables rough coding of stimulus direction. Both types of sensilla respond to the fly at a distance of more than 10 cm. They respond to the low-frequency currents and the oscillations of the air particles with wing beat frequency. The contralateral T1 sensilla respond to wing beat frequency with synchronous firing of action potentials. The firebug can therefore detect potential predators/parasites such as fly, and perhaps based on synchronous firing of action potentials even recognize them.

Pore-forming toxins are an important component of the venom of many animals. Actinoporins are potent cytolysins that were first detected in the venom of sea anemones; however, they are occasionally found in animals other than cnidarians and are expanded in a few predatory gastropods. Here, we report the presence of 27 unique actinoporin-like genes with monophyletic origin in Mytilus galloprovincialis, which we have termed mytiporins. These mytiporins exhibited a remarkable level of molecular diversity and gene presence–absence variation, which warranted further studies aimed at elucidating their functional role. We structurally and functionally characterized mytiporin-1 and found significant differences from the archetypal actinoporin fragaceatoxin C. Mytiporin-1 showed weaker permeabilization activity, no specificity towards sphingomyelin, and weak activity in model lipid systems with negatively charged lipids. In contrast to fragaceatoxin C, which forms octameric pores, functional mytiporin-1 pores on negatively charged lipid membranes were hexameric. Similar hexameric pores were observed for coluporin-26 from Cumia reticulata and a conoporin from Conus andremenezi. This indicates that also other molluscan actinoporin-like proteins differ from fragaceatoxin C. Although the functional role of mytiporins in the context of molluscan physiology remains to be elucidated, the lineage-specific gene family expansion event that characterizes mytiporins indicates that strong selective forces acted on their molecular diversification. Given the tissue distribution of mytiporins, this process may have broadened the taxonomic breadth of their biological targets, which would have important implications for digestive processes or mucosal immunity.