Particle tracking stereomicroscopy in optical tweezers: control of trap shape

We present an optical system capable of generating stereoscopic images to track trapped particles in three dimensions. Two-dimensional particle tracking on each image yields three dimensional position information. Our approach allows the use of a high numerical aperture (NA= 1.3) objective and large separation angle, such that particles can be tracked axially with resolution of 3nm at 340Hz. Spatial Light Modulators (SLMs), the diffractive elements used to steer and split laser beams in Holographic Optical Tweezers, are also capable of more general operations. We use one here to vary the ratio of lateral to axial trap stiffness by changing the shape of the beam at the back aperture of the microscope objective. Beams which concentrate their optical power at the extremes of the back aperture give rise to much more efficient axial trapping. The flexibility of using an SLM allows us to create multiple traps with different shapes

A programmable optical angle clamp for rotary molecular motors

Optical tweezers are widely used for experimental investigation of linear molecular motors. The rates and force dependence of steps in the mechanochemical cycle of linear motors have been probed giving detailed insight into motor mechanisms. With similar goals in mind for rotary molecular motors we present here an optical trapping system designed as an angle clamp to study the bacterial flagellar motor and F(1)-ATPase. The trap position was controlled by a digital signal processing board and a host computer via acousto-optic deflectors, the motor position via a three-dimensional piezoelectric stage and the motor angle using a pair of polystyrene beads as a handle for the optical trap. Bead-pair angles were detected using back focal plane interferometry with a resolution of up to 1 degrees , and controlled using a feedback algorithm with a precision of up to 2 degrees and a bandwidth of up to 1.6 kHz. Details of the optical trap, algorithm, and alignment procedures are given. Preliminary data showing angular control of F(1)-ATPase and angular and speed control of the bacterial flagellar motor are presented

Abstracts from the 20th International Symposium on Signal Transduction at the Blood-Brain Barriers

https://deepblue.lib.umich.edu/bitstream/2027.42/138963/1/12987_2017_Article_71.pd

Vairimorpha apis Versus Vairimorpha ceranae, Replacement or Dynamic Prevalence?

Nosematosis is currently a frequently discussed disease of bees caused by two species of microsporidia: Vairimorpha apis, and Vairimorpha ceranae. Vairimorpha apis represents the original species of Apis mellifera parasite, and Vairimorpha ceranae, is a species introduced from Asia. In the last two decades, epidemiological data on the growth of the prevalence of V. ceranae infection have increased, which has led to its dominant position at the expense of its congener V. apis, practically all over the world. This process is assumed to be the result of asymmetric competition within the host, where V. ceranae, showed a better ability to adapt to higher temperatures, which was first manifested by its spread in warmer climate zones. However, several results of studies from recent years somewhat unexpectedly showed that it is premature to talk about the complete replacement of V. apis by V. ceranae. They pointed to a greater influence of seasonality and average temperatures in winter and summer in a given year on the result of the current prevalence of infection and co-infection of Vairimorpha spp., regardless of the climatic zone in which the colonies were located. Considering the different clinical and subclinical manifestations of infection caused by V. apis, and V. ceranae, and its impact on the defense, survival and productivity of bee colonies, the aim of our work was to analyze the factors affecting the distribution and prevalence of Vairimorpha spp

Body Characteristic of Drones of Different Origin

Computer-based methods help beekeepers and scientists in apidology and bee research. Using software Optika Vision Pro in this study, three body morphological characteristics has been applied to honeybees’ drones (Apis mellifera carnica) of different origin in identification of difference among them. All three measured body morphological characteristics (body length, forewing length, and head length) were statistically different between drones originated from colonies with mated queens and drones originated from colonies with unfertilised queen and/or with unfertilised worker bee(s), respectively, thus making them potentially more successful in queen fertilization and secondary colony development and productivity

Nosema Disease of European Honey Bees

Nosematosis is currently a frequently discussed honey bee disease caused by two types of Microsporidia: Nosema apis and Nosema ceranae. Nosematosis as an intestinal disease caused by these species is one of the main factors associated with the weakening and loss of hives, with none of the stressors acting in isolation and all having an important synergistic or additive effect on the occurrence of parasitic infection. The most important factors are exposure to pesticides and nutritional stress, both worsening the immune response. Honey bees Apis mellifera become more susceptible to parasites and subsequently the disease manifests itself. Choosing the right laboratory diagnostics is important to determine the prevalence of both species. Our review summarizes the most commonly used methodologies, especially polymerase chain reaction (PCR), which is a reliable method for detecting nosematosis, as well as for distinguishing between the two species causing the disease

Molecular Detection of <i>Nosema</i> spp. in Three Eco Regions of Slovakia

Microsporidia are unicellular obligate intracellular parasitic fungi that infect a wide range of vertebrates and invertebrates. There are two known species of microsporidia infecting honey bees in Slovakia- first Nosema apis and also Nosema ceranae. Our aim was to examine samples of honey bees collected from bee queen breeders in three ecoregions of the Slovak Republic in 2021 and 2022. First, microscopic diagnostics were used, and then randomly selected samples were examined using molecular methods. There were 4018 samples examined using microscopic diagnostics and the positivity was demonstrated in 922 samples. From the microscopically diagnosed positive samples, 507 samples were randomly selected, and using molecular methods, the positivity was proved in 488 samples. After sequencing the positive PCR products and comparing the sequences (BLAST) with the sequences stored in the gene bank, the Nosema ceranae species was detected in all positive samples