First insights into the activity of major digestive enzymes in the intestine of the European catfish Silurus glanis and protective anti-enzymatic potential of its gut parasite Silurotaenia siluri.

The European catfish Silurus glanis is attracting growing interest as an object of fisheries and aquaculture, which is reinforced by the expansion of its natural range under climate change. Shaping the effective exploitation strategy for this valuable species requires detailed knowledge of its biology, including feeding and digestion processes, especially near the natural limits of the species range. Meanwhile, the digestion physiology of the European catfish remains poorly explored, including the activity of major digestive enzymes and the possible effect of intestinal parasites on this activity.

Magnetic Fluctuations Entrain the Circadian Rhythm of Locomotor Activity in Zebrafish: Can Cryptochrome Be Involved?

In the 1960s, it was hypothesized that slow magnetic fluctuations could be a secondary zeitgeber for biological circadian rhythms. However, no comprehensive experimental research has been carried out to test the entrainment of free-running circadian rhythms by this zeitgeber. We studied the circadian patterns of the locomotor activity of zebrafish () under different combinations of light regimes and slow magnetic fluctuations, based on a record of natural geomagnetic variation.

Surviving in the fish gut: Comparative inhibitory capacities against the host proteinases in cestodes of the genus Proteocephalus.

Currently, little is known about inhibitory substances enabling tapeworms to settle in fish intestines thereby avoiding proteolysis. Contrary to previous studies with certain host-parasite pairs, this research compares the inhibitory capacities in three tapeworm species of the same genus Proteocephalus from four different fishes (P. torulosus from dace and zope, P.

Localization of the proteinase inhibitor activity in the fish cestode Eubothrium rugosum.

The mechanisms enabling fish tapeworms to avoid proteolytic attacks by digestive enzymes of their fish host have been studied in less detail compared with mammalian cestodes. This study aimed to assess the inhibitory ability towards trypsin and chymotrypsin in Eubothrium rugosum, an intestinal parasite of burbot Lota lota, and establish its localization in the tapeworm. To this end, the worms were treated with Triton X-100 followed by differential centrifugation to isolate the tegumental brush border membrane.

Circadian rhythms in zebrafish (Danio rerio) behaviour and the sources of their variability.

Over recent decades, changes in zebrafish (Danio rerio) behaviour have become popular quantitative indicators in biomedical studies. The circadian rhythms of behavioural processes in zebrafish are known to enable effective utilization of energy and resources, therefore attracting interest in zebrafish as a research model. This review covers a variety of circadian behaviours in this species, including diurnal rhythms of spawning, feeding, locomotor activity, shoaling, light/dark preference, and vertical position preference.

Activity of proteolytic enzymes in the intestine of bream Abramis brama infected with cestodes Caryophyllaeus laticeps (Cestoda, Caryophyllidea).

Adaptive mechanisms underlying the long-term existence of intestinal parasites in their enzymatically hostile environment are still poorly understood, particularly with regard to fish cestodes. The study describes the activity distribution of proteolytic enzymes along the gut of the bream Abramis brama infected with intestinal cestodes Caryophyllaeus laticeps and characterizes the capacity of these worms to inhibit host proteinase activity. Mucosal proteolytic activity was mainly presented by serine proteinases.

Inactivation of proteolytic enzymes by Eubothrium rugosum (Cestoda) from the gut of burbot Lota lota.

Parasitic organisms inhabiting the alimentary canal should permanently resist the destructive action of host digestive enzymes. The intestinal parasites were shown to produce specific protease inhibitors protecting them from proteolysis. However, little is known about this adaptive mechanism in cestodes so far, especially for the tapeworms dwelling inside the fish intestines.

Lateralisation of rotational swimming but not fast escape response in the juvenile sterlet sturgeon, Acipenser ruthenus (Chondrostei: Acipenseridae).

For the first time, behavioural lateralisation was shown in a chondrostean fish (sterlet sturgeon Acipenser ruthenus). A significant directional bias was found in young A. ruthenus swimming along a circular swimway.

Individual-level consistency of different laterality measures in the goldbelly topminnow.

In humans, hemispheric language dominance is, to some degree, associated with handedness. Significant associations have been reported between several other lateralized functions. Much less is known about the organization of cerebral asymmetries in nonhuman species and, in particular, whether the presence of reversed asymmetry of one function is associated with a reversal of other lateralized functions or, instead, if cognitive functions lateralize independently.