Circadian phase relationships of thymidine-3H uptake, labeled nuclei, grain counts, and cell division rate in rat corneal epithelium

Significant differences in the uptake of thymidine-³H, percentage of labeled cells, numbers of grains per labeled nucleus, and mitotic rate were noted in rat corneal epithelium along a 24-hr time scale. These were demonstrated by injecting subgroups of five animals every hour during a 24-hr period with thymidine-³H, sacrificing them 2 hr later, and analyzing the corneal epithelium by scintillation counter and radioautographic techniques. The increase in uptake during specific periods of the 24-hr time scale is attributed to an acceleration in the rate of DNA synthesis by individual cells and to an increase in the percentage of cells in the population actively synthesizing DNA.     

Ethological analysis of social and environmental effects on the distribution of the behavioural elements of the paradise fish (Macropodus opercularis L.)

The behaviour of the paradise fish in a new environment was examined. The influence of space, the number of conspecifics, the number of each sex in the various groups and the time allowed for habituation on the distribution of various behavioural elements were revealed. By means of principal component analysis five biologically meaningful factors were extracted. Using the scores of the various factors as indices of settlement, fear passive behaviours and exploration, special effects of the environment were assessed. In small tanks the fish are in an emotionally low but stable continuously trying to escape. Being prevented from escaping they develop various passive behaviour forms which alternate with escape. In a large tank the main occupation of a female fish on its own is exploration at the start; this is accompanied by a fearful state. In groups of four the activity of exploration is less and the fearful state is not so pronounced. The presence of males seems to secure the most stable state in a new environment though after about two days the males start breeding activities and this involves a new spectrum of activities.     

Locomotor activity of atlantic salmon parr (Salmo salar L.) in various light conditions and in weak magnetic fields

Locomotor activity studies in the laboratory under artificial light cycles co-ordinated with times of sunrise and sunset demonstrated that ten of sixteen Atlantic salmon parr were nocturnal, with an approximately twenty-four hour periodicity. The remaining six fish exhibited diurnal activity patterns or activity mainly after times of light change. Two fish immediately shifted their activity patterns to co-ordinate with a 6-hr shifted light cycle. Six fish retained no activity patterns in constant light, and only two of eleven fish had weak activity patterns in constant darkness. Results suggest that Atlantic salmon parr are dependent on a light-dark cycle for timing their activity rhythms. Three of twelve salmon in an imposed magnetic field four times the strength of the horizontal vector of the ambient field, increased their activity level and changed activity patterns in the increased field. The remaining fish showed no distinct change in locomotor activity.     

THE ROLE OF AUXIN IN THE PHOTOPERIODIC TUBERIZATION IN BEGONIA EVANSIANA ANDR.

The formation of aerial tubers in Begonia plants, an SD response,was inhibited by IAA, NAA and IBA applied to their leaves duringthe dark periods. The effectiveness of IAA differed accordingto the time of application during the dark periods, and themost sensitive time varied with daylengths employed. In order to inhibit the tuberization under optimal photoperiods(8-hr SDs), IAA had to be applied during the first 2 days orso of the SDs. Under non-optimal photoperiods, however, IAAwas effective even when applied somewhat later. The auxin activity of leaf extracts from the plants subjectedto 8-hr SDs decreased during the first 2 or 3 days to a minimum,and then increased until finally began to decrease, again; undernon-optimal photoperiods, the minimum of auxin activity wasattained more slowly. The paper-chromatographic study suggestedthat the change in auxin activity was mainly due to the changein IAA content. The number of SDs making the auxin content minimal agreed withthe minimum number of SDs required for tuberization. On the basis of the above results, the part played by endogenousauxin in photoperiodic induction is discussed. ¹Present address: Institute for Agricultural Research, TôhokuUniversity, Sendai. ²Present address: Biological Institute, Yamaguchi University,Yamaguchi.     

Social status, access to food, and compensatory growth in juvenile Atlantic salmon

Juvenile Atlantic salmon Salmo salar subjected to three weeks of cooler temperatures were 8·5% smaller than controls at the end of the temperature manipulation, but had caught up in size 20 weeks later. The behavioural means is examined by which this catch-up or compensatory growth is achieved. While on average compensating fish did not spend more time feeding, dominant fish within each group gained more exclusive access to the feeding area during periods of catch-up growth. Therefore the extent to which compensatory growth could be achieved was dependent on both the social status of the individual and the dominants' ability to monopolize the food patch.     

异育银鲫易钓性的表型基础和生态结果及饥饿响应

为考察鲤科鱼类易钓性种内差异的表型基础、生态结果及饥饿响应, 研究以异育银鲫(Carassius auratus gibelio)幼鱼为实验对象, 在饥饿前(对照组)测定其表型特征(能量代谢、游泳能力和个性行为)并垂钓, 随后在饥饿1周后再次垂钓(饥饿组), 最后进行2周的恢复摄食生长实验(恢复组)。垂钓实验具有4个重复, 每个重复的样本量为40尾, 垂钓1.5h即停止, 垂钓20尾为钓出组, 剩余20尾为未钓出组。研究发现: 除钓出组的相对代谢空间(FAS)小于未钓出组外, 钓出组的外部形态(体重、体长和肥满度)、能量代谢参数(标准代谢率SMR、最大代谢率MMR和代谢空间AS)、游泳能力(最大匀加速游泳能力U_cat和最大有氧运动能力U_gt)及个性行为(探索性、活跃性和勇敢性)与未钓出组均无明显差异(所有P>0.05); 在经历捕食者模拟袭击后, 实验鱼勇敢性的潜伏时间比大于探索性, 导致勇敢性的运动时间比和穿门频率小于探索性。SMR与U_cat及U_gt不相关(P>0.05), 但MMR和AS与U_cat及U_gt均呈正相关(P<0.05); 能量代谢参数与个性行为存在部分相关。饥饿增加异育银鲫的垂钓总时间、单尾平均垂钓时间和单尾垂钓时间的变异系数。钓出组在饥饿期的特定生长率(SGR)小于未钓出组, 而恢复期钓出组的SGR与未钓出组无显著差异; 除MMR和AS外, SMR与饥饿期及恢复期的SGR均呈负相关(P<0.05), 即SMR越高个体在饥饿期间的体重下降更快, 在恢复摄食后生长却较慢。研究表明: 异育银鲫幼鱼的易钓性可能不具备表型基础, 并且因环境食物匮乏而降低; 虽然饥饿期间两种易钓性表型个体的生态结果存在差异, 但该生长差异在营养恢复后消失, 表明异育银鲫的易钓性具有一定的环境依赖性。     

The role of a social factor in exploration of a novel environment in great tits (Parus major) under conditions of limited space

Sequential tests in an open field (OF) and in an aviary were performed to study the exploration behavior of great tits, Parus major Each aviary of 2×2×2 m included a standard set of objects: trees, feeder, and shelters. Twenty-four aviaries included a single individual, and 49 aviaries included two heterosexual individuals. During the 15-min observation, a number of explored objects, the latent exploration period of each object (the time period from the start of observation to the first visit of each object), and the time period to the onset of feeding were recorded. The exploration rate of each individual was characterized by the sum of all latent periods (CLP). No association between the cumulative locomotor activities in OF and in an aviary was found. Probably, in the complex environment of an aviary, the frequency of directed actions increases, competing with the movement activity. Faster individuals in OF showed a shorter CLP; i.e., they were fast explorers. The exploration rate of a novel environment in the presence of socid partner was unrelated to exploration scores in OF. Interrelations of birds combined in an aviary were dependent on combinations of personality characteristics identified in OF.     

Food-search strategy in ling (Molva molva L.): crepuscular activity and use of space

The activity rhythm and use of space in the food-searching behaviour of ling (Molva molva L.) were studied by means of a stationary positioning system. The system consisted of a fixed array of three hydrophones, which monitored the position of each individual being tracked once every three minutes. Five ling were tagged in situ by allowing them to ingest a transmitter wrapped in bait and were tracked continuously for 6 to 11 days. Ling showed a crepuscular activity rhythm with higher levels of swimming activity at dawn and dusk. The fish occupied a home range throughout the study, and during inactive periods (about 65% of the time) they remained within a small core area. Most of the time spent outside the core area was during the period of high activity at dawn. Food-search behaviour was studied by setting mackerel-baited fishing gear in the experimental area. When baits were present, ling moved more slowly and within a more limited area, indicating area-restricted searching in the presence of a food odour. Ling responded to and located baits in both their active and inactive periods during the day, but were not observed to react at night. Comparing these findings with those from similar tracking experiments on cod (Gadus morhua L.) suggested that ling are less active at night and show a more restricted use of space by occupying a core area. This may reflect different feeding strategies between these gadoid species with ling taking a higher proportion of mobile prey and being more dependent on visual stimuli.     

Electromyograms from radiotelemetry as indicators of reproductive activity in lake trout

One male and one female lake trout, Salvelinus namaycush , were held in a laboratory tank simulating a natural spawning environment. Their behaviour during their reproductive period was videotaped each day for 2 h at dusk. The fish activities were classified into seven types: resting, casual swimming, side-thrusting, chase, chase-nudge, body alignment, shuddering. As the reproductive period progressed the fish became more generally active with a marked increase in interactive behaviours such as pursuit of the female by the male (chasing, chasing-nudging). Around spawning time, shuddering and body alignment activity reached apeak. Each fish was equipped with an internally implanted radiotelemetry package able to detect and transmit continuously over the course of each day signals that reflect production of the electromyograms (EMGs) that accompany fish axial muscle activity (high muscular activity gives low pulse interval times in milliseconds). The lowest EMG pulse intervals corresponded with what, from the video records, appeared to be the time of highest physical activity during the reproductive period–viz. that associated with spawning activity during dusk. Other times during the diel cycles over the reproductive period, except for times of roughly similar duration during early morning (which may also be reflections of spawning) showed considerably lower muscular activity. It is concluded that transmitted EMG records could probably be used as indicators of spawning activity of lake trout in at least some of those places in the field where they cannot normally be located by visual means.     

Hydroacoustic survey on the spatial distribution pattern and day‐night rhythmic behaviour of fishes in the Xiaonanhai reach of the upper Yangtze River

To understand the spatial distribution patterns and fish behaviour in the Xiaonanhai reach of the upper Yangtze River at the end of the Three Gorges Reservoir, four acoustic surveys were carried out over longer periods in 2011 and 2012, which included two boat surveys and two fixed‐station horizontal detections. The results showed that fish assemblages were unevenly distributed in the investigated areas, and were mainly concentrated in the section from Funiuxi to Gaojiatuo. Fish behaviour was found to show a night‐time activity peak. Additionally, fish moved much closer to the riverbank at night than during the day. Considering the intense human activities in this area, some suggestions are offered to mitigate the negative effects of shipping and hydrodam construction by using design and operational logistics to support future fish conservation.     

Translocation and accumulation of translocate in the sugar beet petiole

Accumulation of translocate during steady-state labeling of photosynthate was measured in the source leaf petioles of sugar beet (Beta vulgaris L. monogerm hybrid). During an 8-hr period, 2.7% of the translocate or 0.38 μg carbon/min was accumulated per cm petiole. Material was stored mainly as sucrose and as compounds insoluble in 80% ethanol. The minimum peak velocity of translocation approached an average of 54 cm/hr as the specific activity of the ¹⁴CO₂ pulse was progressively increased. The ratio of cross sectional area required for translocation to actual sieve tube area in the petiole was 1.2. A regression analysis of translocation rate versus sieve tube cross sectional area yielded a coefficient of 0.76. The specific mass transfer rate in the petiole was 1.4 g/hr cm² phloem or 4.8 g/hr cm² sieve tube. Histoautoradiographic studies indicated that translocation occurs through the area of phloem occupied by sieve tubes and companion cells while storage occurs in these cells plus cambium and phloem parenchyma cells. The ability of the petiole to act as a sink for translocate is consistent with the concept that storage along path tissue serves to buffer sucrose concentration in the translocate during periods of fluctuating assimilation.     

Eye colour in juvenile Atlantic salmon: effects of social status, aggression and foraging success

Status-based differences in sclera colour in small groups of juvenile Atlantic salmon Salmo salar , held in a semi-natural environment over a 20 day period, became obvious 3 days after the start of the study and persisted for the 20 days. Dominant fish had pale sclera, and this pattern was very stable over the experimental period. In contrast, the sclera colour of subordinate fish (ranks 2–5) fluctuated from day to day. Median sclera colour offish ranked 4–5 darkened on days they received more aggression, and sclera of rank 2 fish were lighter on days on which they initiated more attacks. Changes in sclera colour of fish ranked 2–4 were more frequent during feeding periods than non-feeding periods. This study confirms that the relationship between eye colour and status described in tanks is also seen in more natural environments, and also that colour change in juvenile salmonids is a complex response to local events.     

Effects of induced wheel running on the circadian activity rhythms of Syrian hamsters: entrainment and phase response curve

The goal of this study was to provide an example of nonsocial and nonphotic entrainment in Syrian hamsters, together with a corresponding phase response curve (PRC). Fourteen male hamsters were given 2-hr bouts of induced activity (mostly wheel running) at 23.83-hr intervals in constant darkness (DD). The activity onsets of 10 hamsters entrained to this manipulation, with no anticipatory activity present. After entrainment, the rhythms resumed free-running from a time 0.66-3.91 hr after the onset of the last bout of induced activity. Postentrainment free-running periods were shorter than pre-entrainment values. The PRC for 2-hr pulses of induced activity in DD revealed phase advances induced in some animals between circadian time (CT) 4 and CT 11 (approximately the last half of the hamsters' rest period), and delays between CT 23 and CT 3 and between CT 17 and CT 20. The CTs for phase advances are compatible with the phase angle differences observed between rhythm and zeitgeber at the end of entrainment. Many features of the results (not all animals entraining, PRC characteristics, lack of observable anticipation to the daily stimuli, phase relationship between zeitgeber and activity rhythms) are similar to those from a previous study on social entrainment in this species (Mrosovsky, 1988). These similarities reinforce the idea that induced activity and social zeitgebers act on activity rhythms via a common mechanism.     

Effects of constant darkness and constant light on circadian organization and reproductive responses in the ram

The relationship between circadian rhythms in the blood plasma concentrations of melatonin and rhythms in locomotor activity was studied in adult male sheep (Soay rams) exposed to 16-week periods of short days (8 hr of light and 16 hr of darkness; LD 8:16) or long days (LD 16:8) followed by 16-week periods of constant darkness (dim red light; DD) or constant light (LL). Under both LD 8:16 and LD 16:8, there was a clearly defined 24-hr rhythm in plasma concentrations of melatonin, with high levels throughout the dark phase. Periodogram analysis revealed a 24-hr rhythm in locomotor activity under LD 8:16 and LD 16:8. The main bouts of activity occurred during the light phase. A change from LD 8:16 to LD 16:8 resulted in a decrease in the duration of elevated melatonin secretion (melatonin peak) and an increase in the duration of activity corresponding to the changes in the ratio of light to darkness. In all rams, a significant circadian rhythm of activity persisted over the first 2 weeks following transfer from an entraining photoperiod to DD, with a mean period of 23.77 hr. However, the activity rhythms subsequently became disorganized, as did the 24-hr melatonin rhythms. The introduction of a 1-hr light pulse every 24 hr (LD 1:23) for 2 weeks after 8 weeks under DD reinduced a rhythm in both melatonin secretion and activity: the end of the 1-hr light period acted as the dusk signal, producing a normal temporal association of the two rhythms. Under LL, the 24-hr melatonin rhythms were disrupted, though several rams still showed periods of elevated melatonin secretion. Significant activity rhythms were either absent or a weak component occurred with a period of 24 hr. The introduction of a 1-hr dark period every 24 hr for 2 weeks after 8 weeks under LL (LD 23:1) failed to induce or entrain rhythms in either of the parameters. The occurrence of 24-hr activity rhythm in some rams under LL may indicate nonphotoperiodic entrainment signals in our experimental facility. Reproductive responses to the changes in photoperiod were also monitored. After pretreatment with LD 8:16, the rams were sexually active; exposure to LD 16:8, DD, or LL resulted in a decline in all measures of reproductive function. The decline was slower under DD than LD 16:8 or LL.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of increased flow on the behaviour of Atlantic salmon parr in winter

The effect of increased flow on movement and microhabitat use of Atlantic salmon Salmo salar parr in winter was investigated using radiotelemetry. To simulate hydropeaking operations, flow was increased four‐fold from 1·3 m³ s⁻¹ to 5·2 m³ s⁻¹ for 24 h periods. Flow did not affect fish habitat use or displacement and had little effect on fish activity within diel periods. During high flow periods in late winter, fish reduced night‐time activity. Stranding rates during flow reduction were also very low (only one fish).     

Atypical 24-hour rhythms of serotonin N-acetyltransferase activity in the rat pineal gland

Previous long-term studies have shown that in the pineal gland of rats melatonin synthesis is subject to infradian rhythms with periods between 4 and 7 days. Since in these studies melatonin-related parameters were measured at one timepoint of a 24-hr cycle only, the aim of the present investigation was to extend these experiments by more frequent sampling, to characterize the infradian rhythmicity in more detail. Male Sprague-Dawley rats kept under a light schedule of LD 12:12 (lights on at 0700) were killed at 6-hr intervals on 8 consecutive days. After decapitation the pineal gland was rapidly dissected out, followed by measurements of one of the melatonin-forming enzymes, serotonin N-acetyltransferase (NAT) activity. It was found that pineal NAT activity exhibited the well known day/night rhythm, i.e. low activity during daytime and strikingly enhanced activity at night, during the first 4 days of the experiment. On the fifth night (from Saturday to Sunday) an unusually high NAT peak occurred at 2400 hr, followed by two atypical 24-hr cycles. In the first cycle the midnight and 0600 hr values were equal and in the second cycle the 0600 hr value was significantly higher than the midnight value. To investigate whether the unusually high NAT peak was a single event or not, four additional short-term experiments were carried out at 2400 hr on 4 consecutive weekends, from Friday to Monday. In each of the four 4-day experiments a distinctly higher peak of NAT activity was found on Saturday, but with time the peaks became less prominent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Origin of esterified cholesterol transported in the very low density lipoproteins of human plasma

In two subjects the specific activity of esterified cholesterol in plasma lipoprotein subfractions was measured for up to 9 hr after an intravenous injection of [(3)H]mevalonic acid. It was found to be consistently higher in larger (S(f) > 100) than in smaller (S(f) 20-100) very low density lipoproteins (VLDL). Four subjects were given an intravenous injection of heparin so that the VLDL could be studied as its concentration fell and subsequently rose again. During the first hour the relative reduction was greatest for triglyceride, intermediate for free cholesterol, and least for esterified cholesterol. Between 1 and 7 hr postheparin, the VLDL pool was restored, but the pattern of increase of individual lipids was not parallel. The triglyceride increment was much greater during the 1-4-hr period than during the 4-7-hr period; in three of the subjects the free cholesterol increment was also greater during the earlier period. The increase in esterified cholesterol, however, was consistently greater during the 4-7-hr period. In six other subjects the specific activity of VLDL esterified cholesterol was related to that of its possible plasma precursors in samples collected at 1-hr intervals for 8 hr after the injection of [(3)H]mevalonic acid. Free cholesterol emerged as the most likely immediate precursor with the possibility of a hepatic as well as an intraplasma origin. The results did not support a major in vivo transfer of esterified cholesterol from high density lipoproteins to VLDL.     

The inheritance of flowering time inAmaranthus species

The inheritance of flowering time was studied in a cross between an early flowering weedy species,Amaranthus retroftexus L., and a late flowering related crop species,A. cruentus L. Segregation ratios were scored in four successive backcrosses of the hybrid to the crop species (BC1 to BC4) and in backcross-derived generations (BC2F2, BC2F3) grown under 8-hr and 16-hr photoperiods and 30/20°C day/night temperatures in growth chambers, and under field and greenhouse environments during summer months at Davis. One major gene for earliness (Ea), dominant over late flowering, was identified conclusively under the 8-hr regime and in some genetic backgrounds under field conditions. Based on segregation patterns within individual progenies and the observed transgressive segregation, a model of three genes seemed to explain all of the ratios consistently. Evidence of segregation distortion at theEa locus, resulting in the deficiency of early individuals, and some role of epistatic interactions among the three postulated major genes requires further testing based on more isogenic and specific progeny materials. Flowering time was closely associated with plant form, inflorescence development, and numerous other traits which differentiate the crop and weed species. This association provides interesting insights into evolutionary changes under domestication and dispersal from lower to higher latitudes.     

Time Learning and Anticipatory Activity in Groups of Arctic Charr

Time learning and anticipatory activity were studied in five groups of 16–17 Arctic charr (Salvelinus alpinus) using self‐feeding devices with individual recognition (PIT (Passive Integrated Transponders)‐tags). The fish were kept under a LD 12:12 h cycle and periods of free access to the food were alternated with periods of time‐limited (2 h) access to food. Self‐feeding activity was significantly related to the light period in unrestricted conditions while related to the feeding periods during time‐limited access to food. The fish learned to concentrate their feeding activity to the restricted mealtime (>50% of the daily self‐feeding activity) within 10 d. The food anticipatory activity, measured as an increased self‐feeding activity before the feeding time and as aggressive interactions close to the trigger, was significant in both cases. The dominant individuals increased the trigger activity in advance of the time‐restricted reward period and subdominant individuals approached the trigger also in advance, inducing aggressive interactions. Thus, anticipating and learning a temporally predictable food source was pronounced in groups of self‐feeding Arctic charr.     

Seasonal variation in diel activity and microhabitat use of an endemic New Zealand stream-dwelling galaxiid fish

1. Seasonal variation in microhabitat use and activity of 14 giant kokopu Galaxias argenteus, a drift‐feeding galaxiid fish, was compared using radiotelemetry. 2. During winter giant kokopu predominantly used low velocities and intermediate depths by night and day. Activity recorded during 24 and 72 h periods indicated that fish were consistently active at night and inactive during the day. Activity data corresponded with point‐in‐time habitat use data, both of which indicated that fish were concealed amongst cover during the day and used open water habitats at night. 3. During summer, giant kokopu used higher water velocities, shallower depths and coarser substrata, particularly at night but also occasionally during the day relative to winter. Giant kokopu were active by both day and night in summer, although periods of activity were less defined and less predictable than during winter. 4. Adults used predictable home reaches at base‐flow, with most individuals repeatedly using of one or two cover locations within their ‘home’ reach. Reaches used by fish were relatively short (rarely exceeding 26 m) irrespective of season and always included a single pool‐riffle sequence. 5. Diel and seasonal behaviour of giant kokopu was generally comparable with that exhibited by other drift feeding fish species in small temperate streams. However, the nocturnal activity of giant kokopu contrasts with activity patterns in various salmonids, indicating that the impact of predation by different drift feeding fish may vary considerably.