Piotr Bebas

• PhD
• Head of Department at University of Warsaw

Circadian rhythmicity is a complex phenomenon that influences human behavior, emotionality and brain activity. A detailed description of individual differences in circadian rhythmicity could inform the design of educational systems, shift-worker schedules, and daily routines. Here we present a comprehensive dataset for studying diurnal rhythms and...

P1036 Poster Session–Basic Human–Day 3. Beyond chronotype: Exploring circadian rhythmicity's influence on reinforcement processing

For years, research on the human biological clock has focused primarily on chronotype (phase of the circadian rhythm). However, a second dimension-distinctness (subjective amplitude) of the rhythm, has so far been overlooked. This study aimed to explore the intricate interplay between psychometric traits and reward-punishment processing, considerin...

The dataset contains structural T1-weighted and functional magnetic resonance brain imaging data, from 37 men (aged 20-30), along with questionnaire-assessed measurements of trait-like eveningness, distinctness, sleep quality, personality type, anxiety levels, sensitivity to punishment and rewards, behavioral inhibition and activation system, atten...

W artykule przedstawiamy historię obserwacji i badań zegara biologicznego – począwszy od czasów Aleksandra Macedońskiego, gdy po raz pierwszy w literaturze znalazł się opis zjawiska cyklu dobowego, poprzez pierwsze badania naukowe wykorzystujące eksperymenty do charakterystyki rytmów u roślin, kończąc na dogłębnej analizie mechanizmu zegara molekul...

Facultative diapause in the wax moth, Galleria mellonella, occurs in the final larval instar. Application of juvenile hormone analogs (JHAs) to the larvae of this species has similar effects to diapause, in terms of prolonged development of the larval stages and the arrest in the metamorphosis of internal organs. Here, we focus on testes developmen...

We compared the internal structure and considered the potential functions of the ephippial walls of several species of Daphniidae. We found that the walls of ephippia in Daphniidae are composed of three interconnected layers of different structure. The external and internal layers, which are relatively solid, are covered by cell-like multiple polyh...

Circadian clocks orchestrate many physiological processes in adult organisms. For example, rhythmic feeding behavior is regulated by the central clock in the nervous system in coordination with metabolic rhythms, which in turn depend mostly on peripheral clocks localized in many tissues. Disruption of the circadian clock leads to metabolic dysregul...

The timekeeping mechanisms that operate at the core of circadian clocks (oscillators) are based on interacting molecular feedback loops consisting of clock and clock‐associated genes. However, there is a lack of comprehensive studies on the expression of clock genes (particularly those forming its core) in single crustacean species at the mRNA and...

Insect hormone analogues are frequently used as insecticides. To compare toxicity of different insect hormone agonists we used the insect SF9 cells originated from the ovary of Spodoptera frugiperda. Cell line SF9 cultured in vitro was exposed to two ecdysteroid mimics – methoxyfenozide and tebufenozide, and two juvenile hormone analogues (JHAs)...

In insects, spermatozoa develop in the testes as clones of single spermatogonia covered by specialized somatic cyst cells (cc). Upon completion of spermatogenesis, spermatozoa are released to the vas deferens, while the cc remain in the testes and die. In the fruit fly Drosophila melanogaster, the released spermatozoa first reach the seminal vesicl...

Insect hormone analogues are frequently used as insecticides. It can lead to the contact of non-target animal species with these compounds. To compare toxicity of different insect hormone agonists we used two cell lines: mammalian, mouse embryonic cells the NIH3-T3T fibroblast and the insect SF9 cells originated from the ovary of Spodoptera frugipe...

Circadian clocks (oscillators) regulate multiple aspects of insect behavior and physiology. The circadian system located in the male reproductive tract of Lepidoptera orchestrates rhythmic sperm release from testis and sperm maturation in the upper vas deferens (UVD). Our previous research on the cotton leafworm, Spodoptera littoralis, suggested rh...

Circadian clocks (oscillators) regulate multiple life functions in insects. The circadian system located in the male reproductive tract of Lepidoptera is one of the best characterized peripheral oscillators in insects. Our previous research on the cotton leafworm, Spodoptera littoralis, demonstrated that this oscillator controls the rhythm of sperm...

Gene silencing through RNA interference (RNAi) has revolutionized the study of gene function, particularly in non-model insects. However, in Lepidoptera (moths and butterflies) RNAi has many times proven to be difficult to achieve. Most of the negative results have been anecdotal and the positive experiments have not been collected in such a way th...

In this report, we show that α-amylase activity is rhythmic in the wild-type fruit fly Drosophila melanogaster, and that this rhythm exhibits the properties of a clock output. Moreover, the rhythm of amylase activity is accompanied by fluctuations in the Amy protein level under 12L: 12D conditions. A strong sexual dimorphism is evident in the oscil...

The clock protein PERIOD (PER) displays circadian cycles of accumulation, phosphorylation, nuclear translocation and degradation in Drosophila melanogaster clock cells. One exception to this pattern is in follicular cells enclosing previtellogenic ovarian egg chambers. In these cells, PER remains high and cytoplasmic at all times of day. Genetic ev...

In Spodoptera littoralis, testicular sperm release occurs in a daily rhythm, which is controlled by endogenous circadian oscillator located in the male reproductive system. Although this rhythm is essential for male fertility, factors that initiate and maintain daily sperm release are not understood. In this study, we investigated a modulatory role...

The period (per) gene is 1 of the core elements of the circadian clock mechanism in animals from insects to mammals. In clock cells of Drosophila melanogaster, per mRNA and PER protein oscillate in daily cycles. Consistent with the molecular clock model, PER moves to cell nuclei and acts as a repressor of positive clock elements. Homologs of per ar...

Circadian clocks regulate multiple rhythms in mammalian tissues. In most organs core clock gene expression is oscillatory, with negative components Per and Cry peaking in antiphase to Bmal1. A notable exception is the testis, where clock genes seem nonrhythmic. Earlier mammalian studies, however, did not examine clock expression patterns in accesso...

The molecular circadian clock regulates multiple cellular processes in a variety of mammalian tissues. In most examined organs, core circadian clock gene expression is oscillatory, with negative clock components, Per and Cry, peaking in antiphase to Clock and Bmal1. A notable exception is the testis, in which previous studies have observed high lev...

Male and female gametes follow diverse developmental pathways dictated by their distinct roles in fertilization. While oocytes of oviparous animals accumulate yolk in the cytoplasm, spermatozoa slough off most of their cytoplasm in the process of individualization. Mammalian spermatozoa released from the testis undergo extensive modifications in th...

Although it is well established that the circadian clock regulates mammalian reproductive physiology, the molecular mechanisms by which this regulation occurs are not clear. The authors investigated the reproductive capacity of mice lacking Bmal1 (Arntl, Mop3), one of the central circadian clock genes. They found that both male and female Bmal1 kno...

The male reproductive tract of Lepidoptera is an ideal model for the study of the physiological role of peripheral clocks in insects. The latter are significant in the generation and coordination of rhythmic phenomena which facilitate the initial stages of sperm capacitation. This process requires the maintenance of pH in the upper vas deferens (UV...

Biological clocks generate daily (circadian) rhythms in various life functions. Insects display a rich variety of circadian behavioral rhythms. These rhythms are associated with daily oscillations in the levels of specific hormones and neuropeptides. Many cellular and molecular processes also vary as a function of time of day. All these rhythms app...

The dichotomous spermatogenesis of many Lepidopterans results in the production of two types of sperm: eupyrene sperm possessing a cell nucleus which participates in fertilisation, and apyrene ones, which lose their nuclei during development and whose function remains a mystery. The goal of our study was to analyse spermatogenesis at the end of the...

Release of sperm bundles from moth testes is controlled by the local circadian oscillator. The mechanism which restricts migration of sperm bundles to a few hours each day is not understood. We demonstrate that a daily cycle of sperm release is initiated by the migration of folded apyrene sperm bundles through a cellular barrier at the testis base....

Reproductive systems of male moths contain circadian clocks, which time the release of sperm bundles from the testis to the upper vas deferens (UVD) and their subsequent transfer from the UVD to the seminal vesicles. Sperm bundles are released from the testis in the evening and are retained in the vas deferens lumen overnight before being transferr...

Recent studies have demonstrated that the peripheral tissues of vertebrates and invertebrates contain circadian clocks; however, little is known about their functions and the rhythmic outputs that they generate. To understand clock-controlled rhythms at the cellular level, we investigated a circadian clock located in the reproductive system of a ma...

Females of the cotton leafworm (Spodoptera littoralis) reared in long day conditions (LD 16:8 h) and mated to males kept throughout the whole period of development in continuous light (LL) oviposit very small numbers of mostly sterile eggs. It was found that in control males reared from the first larval instar in long day conditions there was a lar...

The organization of silk fibroin in pyralid moths Zurovec M, Fedic R, Sehnal F The excellent mechanical properties of insect silk depend on the molecular arrangement of heavy-chain fibroin. Regular iterations of short amino acid repeats in the fibroin molecule allow formation of β-sheets and their stacking into crystallites reinforcing the silk f...

We have investigated patterns of sperm release from the testes of the cotton leafworm, Spodoptera littoralis, a moth which produces an unusually high number of sperm bundles. In a daily cycle of 16h of light followed by 8h of darkness, penetration of sperm bundles through the epithelial barrier separating testicular follicles from the vasa deferent...

The authors examined patterns of spatial and temporal expression of Drosophila per gene homologue in the codling moth, Cydia pomonella. Since sperm release in moths is regulated in a circadian manner by an autonomous clock that is independent from the brain, the authors investigated per expression in male reproductive system along with its expressi...

Females of the cotton leafworm (Spodoptera littoralis) reared in long day conditions (LD16:8h) and mated to males kept throughout the whole period of development in continuous light (LL) oviposit very small numbers of mostly sterile eggs. It was found that in control males reared from the first larval instar in long day conditions there was a large...