CatSper mediates the chemotactic behavior and motility of the ascidian sperm

Sperm motility, including chemotactic behavior, is regulated by changes in the intracellular Ca2+ concentration. The cation channel of sperm (CatSper), plays an important role in the regulation of intracellular Ca2+ concentration. In mammals, CatSper is the only Ca2+channel that functions in the sperm, and the mice that lack the genes for the subunits of CatSper, which make up the pore region of the Ca2+ channel, are infertile due to the inhibition of hyperactivation of the sperm. CatSper is also thought to be involved in chemotaxis in sea urchins. In contrast, in the ascidian, Ciona intestinalis, the sperm-activating and -attracting factor (SAAF) interacts with Ca2+/ATPase, which is a Ca2+-pump. Although the existence of CatSper genes has been reported, it is not clear whether CatSper is the specific Ca2+channel that functions in the ascidian sperm. Therefore, in this study, we generated Catsper3 knockout (KO) animals that found that they were significantly less motile, with few motile sperms not exhibiting any chemotactic behavior. These results suggest that CatSper plays important roles in the spermatogenesis and basic motility mechanisms of sperms in both ascidians and mammals.

Non-Genetic Diversity in Chemosensing and Chemotactic Behavior

Non-genetic phenotypic diversity plays a significant role in the chemotactic behavior of bacteria, influencing how populations sense and respond to chemical stimuli. First, we review the molecular mechanisms that generate phenotypic diversity in bacterial chemotaxis. Next, we discuss the functional consequences of phenotypic diversity for the chemosensing and chemotactic performance of single cells and populations. Finally, we discuss mechanisms that modulate the amount of phenotypic diversity in chemosensory parameters in response to changes in the environment.

Recent Developments in Bacterial Chemotaxis Analysis Based on the Microfluidic System

Bacterial motility in response to chemicals, also called bacterial chemotaxis, is a critical ability to search for the optimal environment to ensure the survival of bacterial species. Recent advances in microbiology have allowed the engineering of bacterial chemotactic properties. Conventional methods for characterizing bacterial motility are not able to fully monitor chemotactic behavior. Developments in microfluidic technology have enabled the designing of new experimental protocols in which spatiotemporal control of the cellular microenvironment can be achieved, and in which bacterial motility can be precisely and quantitatively measured and compared. This review provides an overview of recent developments of and new insights into microfluidic systems for chemotaxis assay.

Electrophysiologic and behavioral responses mediated by volatiles involved in the repellency of Apis mellifera (Lepeletier) (Hymenoptera: Apidae)

Repellent volatiles to insects might be an important tool for management of bees in areas which the presence of these organisms is not required. This study aimed to evaluate the electroantennal and behavioral responses of Africanized honeybees (workers), Apis mellifera (Lepeletier) (Hymenoptera Apidae), at different ages, to benzaldehyde (BA) and methyl anthranilate (MA) and to evaluate the potential repellency of these compounds under field conditions. Laboratory tests were conducted to study electroantennographic responses (mV) and chemotactic behavior of worker bees aged 1-5 (young) and 20-30 (old) days in four choice olfactometer. Electrophysiological responses to each compound did not differ between young and old workers. Bees antennae (young) triggered significantly greater responses to BA, in the older ones, a higher response was observed to MA, both compared to control (ethanol). The threshold response to BA and MA was achieved at 10 µg/µL, both compounds repelled bees at the same dose in olfactometer. Treatments with BA and MA, in field conditions, were less visited by scouter honey bees than those without these compounds (control).

Electrophysiologic and behavioral responses mediated by volatiles involved in the repellency of Apis mellifera (Lepeletier) (Hymenoptera: Apidae)

Repellent volatiles to insects might be an important tool for management of bees in areas which the presence of these organisms is not required. This study aimed to evaluate the electroantennal and behavioral responses of Africanized honeybees (workers), Apis mellifera (Lepeletier) (Hymenoptera Apidae), at different ages, to benzaldehyde (BA) and methyl anthranilate (MA) and to evaluate the potential repellency of these compounds under field conditions. Laboratory tests were conducted to study electroantennographic responses (mV) and chemotactic behavior of worker bees aged 1-5 (young) and 20-30 (old) days in four choice olfactometer. Electrophysiological responses to each compound did not differ between young and old workers. Bees antennae (young) triggered significantly greater responses to BA, in the older ones, a higher response was observed to MA, both compared to control (ethanol). The threshold response to BA and MA was achieved at 10 µg/µL, both compounds repelled bees at the same dose in olfactometer. Treatments with BA and MA, in field conditions, were less visited by scouter honey bees than those without these compounds (control).