Histology and ultrastructure of the gut epithelium of the neotenic cave salamander, Proteus anguinus (Amphibia, Caudata)

Histological, histochemical, and ultrastructural features of the gut of the European endemic cave salamander Proteus anguinus were studied. The gut is a relatively undifferentiated muscular tube lined with a simple columnar epithelium containing numerous goblet cells. The mucosa and underlying lamina propria/submucosa are elevated into a number of high longitudinal folds projecting into the lumen. The enterocytes are covered apically with uniform microvilli. Irregularity in the arrangement of microvilli was observed. Occasionally, irregular protrusions of the cytoplasm appear between groups of microvilli. Pinocytotic activity occurs at the bases of the intermicrovillous space. Mitochondria are numerous in the apical cytoplasm and basally beneath the nuclei. The supranuclear cytoplasm contains most of the cell organelles. The lateral plasma membranes of adjacent cells interdigitate and are joined by junctional complexes. The periodic acid-Schiff (PAS) reaction, indicating neutral mucosubstances, is positive only in the apical brush border of enterocytes and in goblet cells. The goblet cells also stained with Alcian blue (AB), at pH 2.5, thus revealing the presence of carboxylated glycosaminoglycans. Compact aggregations of AB- and PAS-negative cells are situated directly below the epithelium. Mitotic figures are present in individual clusters of cells. The fine structure of cells in these clusters indicated that these cells could be responsible for renewal of intestinal epithelium. Numerous endocrine-like cells could also be seen. The closely packed smooth muscle cells and amorphous extracellular material with collagen fibrils constitute a net-like structure under the basal lamina that is very closely associated with the epithelium. There are numerous acidophilic granular cells between epithelial cells, in the lamina propria/submucosa, and between cells aggregations. They seem to be associated with nematode infections and possibly constitute a humoral defense mechanism.     

Daily and seasonal rhythms of locomotor activity and adrenal function in male hedgehogs(Erinaceus europaeus L.)

Abstract

Male hedgehogs were maintained in outdoor parks, under natural climatic conditions. The general locomotor activity was recorded over one year in five hedgehogs, using an infra‐red producer‐receptor system registering entering or leaving the nest box in relation to time. Simultaneously, thecortico‐adrenal activity was studied monthly by sampling without disturbing, at 4 h intervals over a period of 24 h, in groups of 6 animals with a catheter inserted in the left carotid artery. The corticosteroids were assayed using a competitive protein binding technique.

In our study, hedgehogs living in Western Central France showed:

(1) from February‐March to August‐September a daily nocturnal locomotor activity well synchronized with sunset and sunrise,

(2) between August‐September and February‐March an alternation of resting and activity periods which constitute the hibernating period. The activity periods occur still during the night, but there are no relationships with sunset or sunrise,

(3) from February to October, a nycthemeral rhythm of plasma corticosteroids wi th an evening maximum and a morning minimum, as in laboratory animals with nocturnal locomotor activity,

(4) after October, during hibernation, significant variations of plasma corticos teroids with an irregular.pattern (shifting of the maximum or biphasic profile),

(5) a clearly annual cycle of the daily plasma corticosteroids levels, with a considerable increase in autumn (maximum in December), a significant decrease in January and a minimum from January to May.

These daily and seasonal variations of locomotor activity and cortico‐adrenal activity are related to the seasonal variations of the environment.     

Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms

Theories of extreme lifespan evolution in vertebrates commonly implicate large size and predator-free environments together with physiological characteristics like low metabolism and high protection against oxidative damages. Here, we show that the ‘human fish’ (olm, Proteus anguinus), a small cave salamander (weighing 15–20 g), has evolved an extreme life-history strategy with a predicted maximum lifespan of over 100 years, an adult average lifespan of 68.5 years, an age at sexual maturity of 15.6 years and lays, on average, 35 eggs every 12.5 years. Surprisingly, neither its basal metabolism nor antioxidant activities explain why this animal sits as an outlier in the amphibian size/longevity relationship. This species thus raises questions regarding ageing processes and constitutes a promising model for discovering mechanisms preventing senescence in vertebrates.     

Circadian rhythm in locomotor activity in the burrower crayfish Procambarus acanthophorus (Villalobos 1948)

Crayfish Procambarus acanthophorus is a burrower that spends long periods building deep tunnels to reach the water table during the dry season; thus, its survival entertains a close ecological relationship with the sediment. The aim of this work was to determine whether the properties of the circadian rhythm of locomotor activity could be modified by the sediment availability. Experiments were conducted in both aquaria filled with sediment or filled with water, under cycles of Bright and Dim Illumination (BI:DI, 12:12 h) or under continuous DI:DI. The rhythm of locomotor activity was entrained with the photoperiod in aquaria with sediment or water; however, statistical differences between conditions were obtained comparing the period and the level of activity under free-running. These data suggest that the substrate’s sensorial perception could be encoded as a significant ecological parameter that exerts influence in the physiological mechanisms that control the temporal order in P. acanthophorus.     

Variations in the locomotor activity of the Mexican wolf (Canis lupus baileyi) respect to moon periodicity: a study in an outdoor enclosure

It is assumed that the response of the regulatory system of mammal activity depends on the changes in light intensity throughout the 24-h cycle. The aim of this study was to determine whether the moon luminosity cycle exerts an effect on the locomotor activity of the Mexican wolf (C. lupus baileyi). Data collection was carried out with the actimetry, of 11 individuals were analyzed using ANOVA to determine the effect of the lunar cycle. Significant differences were encountered between moon phases (p = 0.001), with a decrement of activity during new and full moon. However, effects were dependent also on the age of the individuals and the daylight period. On the other hand, it is a possible regulation of the activity pattern by the effect of lunar periodicity. This periodicity needs a more detailed examination to determine its adaptive function.     

Circadian rhythms of demand-feeding and locomotor activity in rainbow trout

Under free-running conditions, most rainbow trout displayed circadian feeding rhythms, although the expression of circadian rhythmicity depended on the experimental condition: 16·7% of fish under constant dim light (LL dim), 66·1% under a 45 :45 min light-dark cycle (LD pulses), and 83·8% under constant light (LL). Under LD pulses, the period length of the free-running rhythms for feeding was significantly shorter (21·9 ± 0·7 h, n =8) than under LL (26·2 ± 0·3 h, n =10). Period length for locomotor activity under LL was 25·8 ± 0·6 h ( n =4). Under LD conditions, the daily demand-feeding profile was always confined to the light phase and chiefly composed of two main episodes, directly after lights on (light elicited) and in anticipation to lights off (endogenous). Contrasting to feeding, the diel locomotor activity profile varied remarkably: a diurnal activity pattern at the bottom, while a clearly nocturnal pattern at the surface. These results contribute to a better understanding of feeding and locomotor rhythms of rainbow trout, providing evidence for the existence of a biological clock involved in their circadian control. This finding contrasts with the previously recorded lack of an endogenous oscillator in the pineal organ driving the rhythmic secretion of melatonin, which suggests different locations from the pineal for the circadian pacemakers in this species.     

Meal size and feeding management strategies influence the daily rhythm of total locomotor activity in horses (Equus caballus)

Keeping and management of horses can induce changes to instinctive and innate behavioural patterns. We investigated the effect of five different management conditions in five groups of horses. All groups were housed in individual boxes under natural environmental and lighting conditions. They were fed three times a day (07:00, 12:30 and 20:00) and had free access to water. Group A was fed with 8 kg/capo/die of hay divided in the three meals. Group B was fed with 8 kg/capo/die of an unifeed divided in the three meals. Group C was fed with unifeed at 07:00 and 12:30 and with hay at 20:00. They were kept in wood-bedded boxes. Groups D and E were fed with unifeed at 07:00 and 12:30, respectively, and in the other, two meals received hay. They were kept in straw-bedded boxes. Our results showed a daily rhythm of total locomotor activity in all groups, influenced by management conditions. Group A engaged in meal patterns similar to those seen in grazing animals. Groups B and C showed the highest MESOR values due to a high searching behaviour. Group C showed a nocturnal acrophase contrary to the other groups. Groups D and E showed a total locomotor activity pattern similar to that observed in Group A probably due to an increase in straw-bedding consuming. The reduction of fibre in diet has an impact on physiology and behaviour of horses. The valuation of diet and in bedding provided to horses kept in box is useful to guarantee the maintenance of the physiological daily rhythm of total locomotor activity.     

Seasonal change in the locomotor activity rhythm of the medaka,Oryzias latipes

A group of the medaka,Oryzias latipes (Cyprinodontidae, orange-red variety, 25 males and 25 females), was kept in an aquarium, which was placed outdoors under natural conditions from December 1984 to January 1986. Locomotor activity at three layers (upper, middle, and lower layers) was recorded with a phototransistor system in each season. In summer, the fish showed typical diurnal activity at all three layers and the activity was greater than in other seasons. However, in autumn and winter, the fish became less active and showed relatively high activity at night at the upper or middle layer and diurnal activity at the lower layer. Nocturnal activity seemed to appear when the water temperature was decreased and the photoperiod was shortened. A free-running activity rhythm was also recorded under continuous darkness (DD) in each season; however, the fish showed clear free-running activity rhythms under DD only in summer.     

Voluntary locomotor activity mitigates oxidative damage associated with isolation stress in the prairie vole (Microtus ochrogaster)

Organismal performance directly depends on an individual''s ability to cope with a wide array of physiological challenges. For social animals, social isolation is a stressor that has been shown to increase oxidative stress. Another physiological challenge, routine locomotor activity, has been found to decrease oxidative stress levels. Because we currently do not have a good understanding of how diverse physiological systems like stress and locomotion interact to affect oxidative balance, we studied this interaction in the prairie vole (Microtus ochrogaster). Voles were either pair housed or isolated and within the isolation group, voles either had access to a moving wheel or a stationary wheel. We found that chronic periodic isolation caused increased levels of oxidative stress. However, within the vole group that was able to run voluntarily, longer durations of locomotor activity were associated with less oxidative stress. Our work suggests that individuals who demonstrate increased locomotor activity may be better able to cope with the social stressor of isolation.     

Photic entrainment of daily rhythm pattern of locomotor activity in sea bass (Dicentrarcus labrax)

The aim of this study was to evaluate the circadian rhythm of daily locomotor activity in sea bass exposed to three different artificial lighting regimes including 12/12, 24/0, and 0/24 L/D periods, and scheduled daytime feeding. Daily rhythm of locomotor activity during 12/12 L/D was observed, whereas locomotor activity recorded during 24/0 and 0/24 L/D resulted arrhythmic. Statistical differences in mesor values among the photoperiods and between light and dark phases of each photoperiod were found. During the 12/12 and 0/24 L/D, the fish were active mostly during the light phase. During 24/0 L/D, a phase inversion occurred. The results showed that photoperiod is a dominant synchronizer in sea bass, and that the appetite in this fish follows daily rhythms which does not match the imposed feeding schedule, suggesting the absence or the lability of internal process that couples feeding cycles and biological rhythms.     

The effects of Tat protein on locomotor activity and circadian gene expressions in the mouse hypothalamus

Transactivator (Tat), a regulatory protein of HIV-1, plays a very important role in HIV-1 infection by promoting the rapid replication of HIV. Research surrounding Tat protein function has mainly focused on inhibition of the immune system, promotion of growth of vascular endothelial cells, and nervous system damage. To date, very little research has addressed the role of Tat in circadian rhythms. Previous studies in our lab have found that the concentration of Tat protein in HIV patients’ blood was positively correlated with patients’ sleep quality and melatonin concentrations. In this study, we applied a Tat expression plasmid in mice. Result demonstrated that the locomotor activities of mice and the concentration of melatonin were significantly increased. Alternatively, the expression of Clock gene was markedly decreased. On the other hand, the expression of the Cry1 gene was significantly increased, while the expression of Bmal1 and Per1 genes exhibited no significant difference.     

The effect of feeding regime on growth, locomotor activity pattern and the development of food anticipatory activity in greenback flounder

The mean final weight of juvenile greenback flounder Rhombosolea tapirina fed a single daily meal during the scotophase was lower than that of groups fed continuously or fed twelve, six, three or one meal during the photophase. Final weight did not differ among the latter five groups. Size variation in all groups of fish decreased during the course of the trial over 120 days. Groups assigned to a higher frequency (and hence a longer total daily meal duration) of daily meals were less active during mealtime. A distinct food anticipatory effect was observed in the groups of fish receiving a single daily meal during either photophase or scotophase, and also developed before at least one meal in the group of fish fed three meals per day.     

Emergence rhythms and protandry in relation to daily patterns of locomotor activity inTrichogramma species

Summary In insect parasitoids, the mating structure of the population depends on the emergence pattern of adults and on their behaviour after emergence. In order to study some aspects of these characteristics in four species of egg parasitoid of the genusTrichogramma, laboratory experiments using automatic video analysis are performed. Adult emergence is concentrated in the morning, with an earlier time for males. The variability of the time of emergence is under genetic control. The relationships between the emergence pattern and the locomotor activity are considered by measuring individually: first, the delay between the emergence and the first locomotion which is significantly greater in females than in males and, second, the activity of newly emerged males, which is maximum at the time of the emergence of females. The locomotor activity is influenced by mating; mated females are much more active than virgin ones, mated males are less active than virgin ones. The adaptive values of the rhythmicity of emergence and of protandry are discussed together with their relationship with the patterns of locomotor activity. The results are also considered with respect to mating strategies in insect parasitoids; they actually support the hypothesis of mating occurring principally among individuals native to the same host patch inTrichogramma species.     

Effects on temperature on spontaneous and thyroxine-stimulated locomotor activity of Atlantic cod

Spontaneous locomotor activity of cod Gadus morhua maintained at 6° C tripled from February to May. In contrast, locomotor activity of cod held at 2° C was significantly lower than at 6° C (between 25 and 65% lower) and the seasonal increase was smaller. Plasma levels of both thyroxine (T₄) and triiodothyronine (T₃) did not differ between 2 and 6° C. T₄ injection increased locomotor activity by 10% for both temperature regimes. These data indicate that low water temperature reduces locomotor activity associated with migration in cod and that thyroid hormones are not involved in this decrease. This study provides a possible mechanism through which cold waters may affects migration and distribution of cod via its Effects on locomotor activity and swimming speed.     

Diel and seasonal locomotor activity patterns in Arctic charr, Salvelinm alpinus (L.)

One-year-old Arctic charr, Sulvelinus alpinus (L.), of the Hornavan strain were tested from February 1985 to January 1986 in an attempt to get an increased understanding of the annual rheotactic behaviour as well as the die1 and seasonal locomotor activity pattern. An annular stream tank equipped with photocells was used to measure the direction of swimming movements as well as the number of passings. From February to late May the locomotor activity was low but increased in July and peaked in September. After November the locomotor activity was again at low winter levels. During the activity peak from July to November the majority ofall movements was directed against the current while no preference for direction was noted during the rest of the year. The high level of swimming movements directed against the current in late summer and autumn may be related to an innate habitat change. From February until June, the charr exhibited a bimodal diurnal activity pattern. In July activity was evenly spread over the whole 24- hour period and in August and September activity was again mainly diurnal with a bimodal pattern. In October and November the activity was mainly nocturnal and in December and January activity was concentrated in the short light period. Both annual and die1 activity are discussed in relation to earlier findings in general locomotor activity in Arctic charr and other salmonids.     

Toward a preliminary assessment of the diversity and origin of Cyprinid fish genus Carassius in Iran

Introduction of non-native fish species has been criticized as one of the major threats to freshwater ecosystems. During recent years, the cyprinid fish genus Carassius has been the subject of various studies in terms of introduction biology and ecology. The taxonomy and identification of described species in the genus Carassius is still ambiguous. In order to increase the knowledge of introduced species of the genus in Iran, molecular approaches were employed to identify species based on the mitochondrial gene, cytochrome b (Cyt b). In total, 417 specimens across Eurasia and some other parts of the world have been analyzed. Afterwards, investigation of the possible origin and pathways of introduction was done using analysis of haplotype networks based on the Cyt b gene. The results revealed that there are three introduced species i.e., Carassius auratus, Carassius gibelio and Carassius langsdorfii, in inland waters of Iran. Carassius langsdorfii was recorded from Iran and western Asia for the first time. Analysis of haplotype network showed various potential sources of introduction for each species in Iran and regions beyond their native distribution ranges.     

Trade-off between pre and post-copulatory traits depends on locomotor activity in male Tribolium castaneum beetles

Locomotor performance is an indicator of dynamic exercise; thus, it is a central trait in many animal behaviours. Although higher locomotor endurance may increase male reproductive success (e.g., in mate searching and male–male contests), investment in other male reproductive traits (e.g., male attractiveness and sperm competition) may be decreased through energy consumption due to higher activity levels. Here, I investigated male attractiveness, mating success, and paternity success using males of the red flour beetle Tribolium castaneum selected for higher (H) and lower (L) locomotor endurance. Although there was no difference in male attractiveness between the selection regimes, H males had significantly higher mating success than L males. Conversely, L males had significantly higher paternity success than H males. Therefore, there was a trade-off between mating success and paternity success among the selection regimes, suggesting that locomotor endurance affects male reproduction in T. castaneum, and individual variation of locomotor endurance may be maintained within a population.     

Light and dark rations and the photic entrainment of circadian locomotor activity patterns in the South American Silver Catfish (Rhamdia quelen,Quoy & Gaimard, 1824)

The aim of this study was to evaluate the daily rhythm of locomotor activity in Rhamdia quelen (R. quelen). A total of 30 fish were enrolled in the study and were equally divided in 10 groups and maintained in 100 liters tanks. The locomotor activity was measured in fish maintained under the LD 12:12 photoperiod regime; thereafter, the LD cycle was reversed to DL in order to study the resynchronization and to explore the endogenous pacemaker. Subsequently, the fish were subjected to constant conditions of light to test whether or not locomotor rhythms are regulated by the endogenous circadian clock. The effect of increasing light length and intensity was studied on daily rhythm of locomotor activity of fish. Our results showed that the R. quelen is a strictly diurnal species, the rhythm of locomotory activity resynchronized quickly after inverting the LD cycle and persist under free course LL, suggesting a circadian origin. The light showed a significant masking effect often blocking the expression of the biological rhythm. The strictly diurnal behavior is controlled directly by the photoperiod and maintained even under very dim light (30 lux).