Timing and plasticity of shoaling behaviour in the zebrafish, Danio rerio

The zebrafish has become a major model system for biomedical research and is an emerging model for the study of behaviour. While adult zebrafish express a visually mediated shoaling preference, the onset of shoaling behaviour and of this preference is unknown. To assess the onset of these behaviours, we first manipulated the early social environment of larval zebrafish subjects, giving them three model shoaling partners of the same pigment phenotype. We then assayed the subjects' preferences using binary preference tests in which we presented subjects with two shoals, one shoal of fish exhibiting the same pigment pattern phenotype as their models and another shoal with a radically different pigment pattern. To determine whether or not the visually mediated preference could be altered once it was established, we further manipulated the social environment of a number of subjects, rearing them with one model shoal and testing them, then changing their social consorts and retesting them. Our results demonstrate that larval zebrafish shoal early in their development, but do not exhibit a shoaling preference until they are juveniles. Moreover, we find that the shoaling preference is stable, as changing the social environment of fish after they had acquired a preference did not change their preference. These data will facilitate investigations into the mechanisms underlying social behaviour in this vertebrate model system.     

Daily shoaling patterns in the zebrafish Danio rerio

Shoaling intensity in zebrafish Danio rerio is believed to vary throughout subjective day and night hours. This experiment examines long term variations in shoaling behavior. Adult zebrafish Dan io rerio were maintained under a 12：12 LD cycle （with dim red light serving as reduced visibility during subjective dark hours）, and their shoaling behavior was monitored every hour for a three-day period of time. Our results show that zebrafish perform shoaling behavior throughout subjective day and under reduced visibility conditions, although mean shoaling times during the light phase were significantly higher than mean shoaling times during the dark phase. However, on the 3^rd day of the experiment, mean shoaling times during the subjective night had increased and mean shoaling times during the subjective day had decreased. This shift in intensity was not seen on the first two days of the study, and may represent the influence of experience on the behavior of the test fish. We believe this study shows that shoaling behavior changes with light/dark cycles and that fish shoal even during reduced visibility conditions.     

Daily variation in the shoaling behavior of zebrafish Danio rerio

Shoaling behavior provides numerous fitness benefits for fish,including enhanced access to mates,increased success in foraging and protection from predators.We were interested in determining whether shoaling intensity differed throughout the day.To do this we kept adult zebrafish Danio rerio in different lighting conditions for 10 days:“Normal” (12:12LD,lights on at 0800 hrs),“Reverse” (12:12LD,lights on at 2000 hrs),DD,or LL,and then observed the shoaling behavior at different times during the day.Our findings suggest that daily variations exist in shoaling behavior,with mean shoaling times for fish from the ‘normal' group being the lowest at the mid-point of the dark phase in the fish's subjective day (00:00 hrs),then rising significantly throughout the day,reaching their highest intensity at 20:00 lrs (lights out).Fish from the “reverse” LD cycle (lights on at 20:00 hrs) showed differences in the mean shoaling times at different times of day,but did not show a gradual increase in shoaling throughout their subjective day.Fish from the DD and LL groups did not show significant differences in the mean shoaling values at different times of day,suggesting that the differences observed in LD fish may not represent circadian rhythms.Therefore,these results demonstrate the existence of daily variations in the shoaling behavior of fish and suggest that environmental cues in the form of light/dark cycles play an important role in regulating these variations [Current Zoology 58 (1):129-137,2012].     

The effect of shoal size on patterns of body colour segregation in mollies

Individual white and black mollies Poecilia latipinna spent significantly more time near the larger group when given the choice between two shoals of similar colouration to themselves. When given the choice between a large and a small shoal of dissimilar colouration to themselves, black test fish spent significantly more time with the larger shoal while white test fish showed no preference for either group. Both white and black mollies chose the smaller of two shoals when given the choice between a large dissimilarly coloured shoal and a small similarly coloured shoal. The results indicate that mollies actively discriminate between shoals on the basis of both body colour and shoal size. However, body colour segregation appears to have a stronger influence on shoal choice.     

The behaviour and ecology of the zebrafish, Danio rerio

The zebrafish Danio rerio, is an important model organism in developmental genetics, neurophysiology and biomedicine, but little is known about its natural ecology and behaviour. It is a small, shoaling cyprinid, native to the flood-plains of the Indian subcontinent, where it is found in shallow, slow-flowing waters. Zebrafish are group spawners and egg scatterers, although females are choosy with respect to sites for oviposition and males defend territories around such sites. Laboratory studies of zebrafish behaviour have encompassed shoaling, foraging, reproduction, sensory perception and learning. These studies are reviewed in relation to the suitability of the zebrafish as a model for studies on cognition and learning, development, behavioural and evolutionary ecology, and behavioural genetics.     

麻醉剂MS-222对斑马鱼行为的影响

实验室条件下观察并测定了斑马鱼(Danio rerio)在不同MS-222浓度处理下的麻醉行为、斑马鱼在高剂量MS-222致死过程中的行为变化、MS-222对斑马鱼摄食条件反射的影响。试验表明:(1)斑马鱼的麻醉行为是一个渐变的过程,可分为不被麻醉(Ⅰ)、轻度麻醉(Ⅱ)、中度麻醉(Ⅲ)深度麻醉(Ⅳ);(2)不同MS-222浓度下斑马鱼进入不同麻醉程度的时间有差异;(3)经MS-222处理900s过程中,80-90mg·L^-1浓度组进入Ⅲ级麻醉程度并有100%的存活率,而麻醉浓度在100mg·L^-1以上时可以迅速在49s内使鱼进入Ⅲ级麻醉程度以及在178s后即可进入Ⅳ级麻醉程度,并在中度麻醉和深度麻醉的过渡中死亡,存活率不超过10%;(4)MS-222对摄食条件反射影响的试验中,光刺激-不麻醉、无光刺激-不麻醉、光刺激-麻醉、无光刺激-麻醉四组班马鱼从投喂到摄食所用时间分别为12.06±1.34s、13.20±1.13s、56.56±56.48s、36.20±25.74s,麻醉组的摄食速度慢于对照组,说明MS-222影响了斑马鱼的摄食条件反射。     

Effect of triclosan exposure on mortality and behavioral changes of Poecilia reticulata and Danio rerio

Triclosan (TCS), a chemical used for its antibacterial properties, is an ingredient in many detergents, soaps, deodorants, cosmetics, antimicrobial creams, toothpastes, and an additive in various plastics and textiles. The behavioral changes at different TCS concentrations (0.001–0.002–0.005–0.01–0.02–0.05–0.1–0.2–0.5 mg/L) were determined for the each test organisms in the study. The synthetic freshwater has temperature 20 ± 2°C, dissolved oxygen 7.0 ± 2 mg/L, pH 7.0–8.0. All experiments were replicated three times, in 14 h light, 10 h dark incubations, 10 fishes were put to each aquarium. In hourly and daily observations, times of dead and number for Poecilia reticulata, Danio rerio were recorded. Behavioral changes of Poecilia reticulata and Danio rerio were observed, such as fast-moving, uncontrolled swimming, trying to escape out of the water, vertical action to the water surface, loss of balance, respiratory difficulties, chills, and inversion.     

微囊藻毒素对斑马鱼重要细胞因子表达的影响

微囊藻毒素是一种肝毒素,它攻击的靶位是肝细胞,能导致鱼的肝脏发生病理变化。该研究以斑马鱼为研究对象,采用RT-PCR方法研究了微囊藻毒素对斑马鱼白细胞介素1β(Interleukin 1β,IL-1β),白细胞介素8(Interleukin 8,IL-8),白细胞介素10(Interleukin 10,IL-10),干扰素(Interferon,IFN),肿瘤坏死因子(Tumor Necrosis Factor,TNF),CXC,CXCa等几个重要细胞因子表达的影响。实验表明,25d时,仅毒素组的斑马鱼肝中有IFN和TNF表达。35d时,毒素组斑马鱼鳃中表达了IL-10,肝中表达了CXCa;毒素组和对照组的斑马鱼肝中都表达了IL-1β,TNF,IL-10,CXC,IFN,且其IL-1β,TNF,IL-10的条带亮于对照组。45d时,IFN仅在毒素组鱼鳃和肝中检测到表达;CXC仅在毒素组的鳃中检测到表达;IL-10在对照组的鳃、肠、肾和肌肉中有表达,在毒素组的肝、卵、肾、肌肉中有表达;IL-1β在对照组和毒素组的肝、卵、肾和肌肉中均有表达,且其条带亮于对照组。结果表明:毒素组斑马鱼的肝和鳃组织发生了炎症反应。这为进一步研究微囊藻毒素对鱼类免疫系统的毒害作用奠定了基础。     

Olfactorily-mediated cortisol response to chemical alarm cues in zebrafish Danio rerio

Chemical cues released as a by-product of predation mediate antipredator behaviour, but little is known about the physiological responses to olfactory detection of predation risk. In this study, zebrafish Danio rerio were exposed to either chemical alarm cues from conspecifics, or water (control). Compared with water controls, D. rerio exposed to alarm cues responded behaviourally with antipredator behaviours such as erratic dashing and an increase in time spent near the bottom of the test aquarium. Danio rerio were sacrificed 5 min after exposure to test cues (alarm cues or water). Enzyme-linked immunosorbent assay (ELISA) revealed whole-body levels of cortisol that were significantly higher for fish exposed to alarm cues (mean ± SE, 11.9 ± 3.4 ng g⁻¹) than control fish (1.5 ± 0.7 ng g⁻¹). These data provide a benchmark for future studies of the proximate mechanisms of olfactorily mediated antipredator responses, modelling effects on aquatic life in a changing climate and, as a model organism, Danio rerio can further our understanding of anxiety in humans.     

Two tachykinin‐like peptides from skin secretions of Danio rerio

Tachykinin perform multiple physiological functions such as smoothing muscle contraction, vasodilation, inflammation, the processing of nerve signal, neuroprotection and neurodegeneration. Two novel tachykinin‐like peptides named tachykinin‐DR1 and ‐DR2 were identified from skin secretions of Danio rerio in current work. Their amino acid sequences were determined as SKSQHFHGLM‐NH₂ and NKGEIFVGLM‐NH₂, respectively. They share a conserved FXGLM‐NH₂C‐terminal consensus motif. By cDNA cloning, the precursor encoding both tachykinin‐DR1 and ‐DR2 was screened from the skin cDNA library of D. rerio. Tachykinin‐DR1 and ‐DR2 share the same precursor, which is composed of 108 amino acid (aa) residues. Regarding the biological activity, tachykinin‐DRs could induce the contraction of isolated strips of guinea pig ileum just like other tackykinins. To our best knowledge, this is the first report of tachykinin from fish skin. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.     

Parent-of-origin specific effects on the methylation of a transgene in the zebrafish,Danio rerio

We have examined the inheritance of a transgene locus in the zebrafish, Daniorerio and demonstrated that its methylation is af fected by the sex of the parent contributing the allele. This parent-of-origin effect on the zebrafish transgene appears to be identical to imprinting as seen in mammals except that in zebrafish, passage of the locus through a female tended to decreased its methylation, whereas passage through a male increased it. Methylation of the transgene in gametic tissues differed from somatic tissue with the locus being hypomethylated in sperm and hypermethylated in the unfertilized egg. The potential identification of imprinting in the zebrafish has important ramifications with respect to the evolution of the process as well as for understanding the role of imprinting in mammals. © 1995 Wiley-Liss, Inc.     

Juvenile convict cichlids shoaling decisions in relation to shoal size and age

Many animals form groups and socialize in response to evolutionary pressures such as predation, food availability, and mate acquisition. Evidence of social choice based on various phenotypic characters (Group Phenotypic Composition [GPC]) has been observed in several animal species. In addition to the physical characteristics of the social group, it is also interesting to consider how decisions of who to socialize with might be expected to change for an individual over time. Younger individuals with limited life experience may discriminate differently between social groups than older conspecifics who have had the opportunity to learn and who may be faced with different ecological or environmental pressures. Here, we used a traditional two‐choice design to explore the shoaling behavior of juvenile convict cichlids and determine whether the number of fish and/or the size/life stage of the individuals within a shoal influenced social choices. We found that juvenile convict cichlids spent more time shoaling with similarly sized juvenile individuals and also preferred to shoal with larger shoals, but not when shoals were comprised of adult fish. The size of the individuals in a shoal was a more influential factor than the size of the shoal itself. Size of individual juveniles was correlated with tendency to visit shoals, but was not correlated with overall time spent shoaling, regardless of shoal composition. As juveniles, convict cichlids can make discriminatory choices that are influenced by specific aspects of shoal composition.     

Influence of familiarity on shoaling behaviour in Texas and blacktail shiners

The Texas shiner Notropis amabilis and the blacktail shiner Cyprinella venusta demonstrated statistically significant preferences for the side of the tank holding their familiar shoalmates, and significantly stronger shoaling behaviour with their familiar shoalmates, than with unfamiliar fish.     

斑马鱼胚胎发育中细胞凋亡的研究进展

细胞凋亡是细胞在基因调控下发生的主动消亡过程,在脊椎动物胚胎发育过程中非常重要。斑马鱼作为一种十分理想的发育分子生物学研究模型,在有关细胞凋亡在诸如形态发生、性别分化等方面功能之活体在位研究中日益受到重视。目前,斑马鱼胚胎发育中主要凋亡通路研究已进行了不少工作,特别是caspase及其它凋亡调控基因在斑马鱼中已被成功克隆,通过转基因斑马鱼胚胎中胁迫诱导细胞凋亡并研究其信号通路以及斑马鱼胚胎形态发生的异常改变,为阐明这些凋亡调控基因与发育之间的关系提供了一个强有力的手段。     

斑马鱼繁殖内分泌学研究进展

作为四大模式动物之一,斑马鱼(Danio rerio)广泛应用于胚胎学、发育生物学、毒理学、分子生物学等研究。但关于斑马鱼繁殖内分泌生理和环境毒理方面的研究少见报道,本文综述了近年来,在内分泌学方面以斑马鱼作为实验动物的研究概况。     

Myogenesis and molecules— insights from zebrafish Danio rerio

Myogenesis is a fundamental process governing the formation of muscle in multicellular organisms. Recent studies in zebrafish Danio rerio have described the molecular events occurring during embryonic morphogenesis and have thus greatly clarified this process, helping to distinguish between the events that give rise to fast v. slow muscle. Coupled with the well-known Hedgehog signalling cascade and a wide variety of cellular processes during early development, the continual research on D. rerio slow muscle precursors has provided novel insights into their cellular behaviours in this organism. Similarly, analyses on fast muscle precursors have provided knowledge of the behaviour of a sub-set of epitheloid cells residing in the anterior domain of somites. Additionally, the findings by various groups on the roles of several molecules in somitic myogenesis have been clarified in the past year. In this study, the authors briefly review the current trends in the field of research of D. rerio trunk myogenesis.     

斑马鱼对无氧运动训练的适应性变化

该研究以斑马鱼为(Danio rerio)对象,研究了四周无氧运动训练对斑马鱼行为、形态、生长、肌肉生化组分及代谢酶活性的影响。旨在探索斑马鱼对无氧运动训练的适应性变化,为进一步了解鱼类适应无氧运动训练的分子机制提供基础数据。结果发现:斑马鱼的日常活跃程度经四周无氧运动训练后显著降低,群聚程度增加;训练组个体体重和体长增长减缓,更利于运动;肌糖原含量显著增加,运动持久能力加强;肌肉乳酸脱氢酶(LDH)活性显著增高,柠檬酸合成酶(CS)活性显著降低,无氧代谢能力加强。即,斑马鱼无氧运动能力和无氧代谢能力在训练后得以明显提升。     

Acoustic observation of diel vertical migration and shoaling behaviour in Atlantic redfishes

Acoustic methods were used to study Atlantic redfishes Sebastes spp. vertical migration and shoaling behaviour in Newfoundland waters. Redfishes exhibited consistent patterns of vertical migration in winter, spring and summer, but pelagic shoals were not observed in winter. Pelagic daytime aggregations were generally in close proximity to dense patches of redfishes along the sea floor. Pelagic shoals exhibited high degrees of variability in size, shape and density. Attempts to explain variations in shoal density and area with features of shoal position and structure were unsuccessful. Nearest neighbour distance between fish in shoals had a lower limit near one body length. During the night, fishes were dispersed in the water column and distributions were more homogenous. Diel vertical migration appeared to be a foraging strategy, in which redfishes followed the migration of their euphausiid prey.     

The cycling gonad: retinoic‐acid synthesis and degradation patterns during adult zebrafish Danio rerio oogenesis

The expression pattern of genes coding for enzymes of the retinoic acid (RA) synthetic and degradation pathways was characterized in adult female zebrafish Danio rerio. Females were conditioned until maturation and post‐spawn expression dynamics were determined. A striking upregulation of cyp26b1, but not cyp26a1, was observed following egg deposition, decreasing to initial levels during recovery. A similar, yet lower, fluctuation was observed for aldh1a2 and rdh10a, the enzymes participating in the two‐step RA biosynthesis cascade. The present work highlights the dynamics of the adult D. rerio oogenesis and uncovers novel, yet elusive, metabolic contributors. Possible compartmentalized roles for the different gene paralogue isoforms are discussed.