Effects of the pO2 on swimming activity and food utilization in ophiocephalus striatus

The obligatory air-breathing fish Ophiocephalus striatus, fed on goat-liver, surfaced 906 times, swimming 270 m/day in aerated water (mean pO₂: 151 mm Hg) and 883 times, travelling 325 m/day in non-aerated water (92 mm Hg); surfacing and swimming activities increased below the pO₂ of 74 mm Hg. Hanging duration was more (8.4 hr/day) in the aerated series than that in the non-aerated series (5.9 hr/day). Rates of feeding, absorption and metabolism of either series averaged to 131,126 and 93 (= 0.8 ml O₂/g/hr) g cal/g live fish/day. Conversion rate and efficiency slightly increased from 22 g cal/g/day and 17% in the aerated series. Culturing O. striatus in aerated waters may not be advantageous. Starving groups in the aerated and non-aerated aquaria surfaced 317 times, hung for 14.7 hr, and swam 61 m/day, expending 15 g cal/ g/day (= 0.1 ml O₂/g/hr).     

Effect of bright light therapy on delayed sleep/wake cycle and reaction time of athletes participating in the Rio 2016 Olympic Games

This study investigated the effect of using an artificial bright light on the entrainment of the sleep/wake cycle as well as the reaction times of athletes before the Rio 2016 Olympic Games. A total of 22 athletes from the Brazilian Olympic Swimming Team were evaluated, with the aim of preparing them to compete at a time when they would normally be about to go to bed for the night. During the 8-day acclimatization period, their sleep/wake cycles were assessed by actigraphy, with all the athletes being treated with artificial light therapy for between 30 and 45 min (starting at day 3). In addition, other recommendations to improve sleep hygiene were made to the athletes. In order to assess reaction times, the Psychomotor Vigilance Test was performed before (day 1) and after (day 8) the bright light therapy. As a result of the intervention, the athletes slept later on the third (p = 0.01), seventh (p = 0.01) and eighth (p = 0.01) days after starting bright light therapy. Regarding reaction times, when tested in the morning the athletes showed improved average (p = 0.01) and minimum reaction time (p = 0.03) when comparing day 8 to day 1. When tested in the evening, they showed improved average (p = 0.04), minimum (p = 0.03) and maximum reaction time (p = 0.02) when comparing day 8 to day 1. Light therapy treatment delayed the sleep/wake cycles and improved reaction times of members of the swimming team. The use of bright light therapy was shown to be effective in modulating the sleep/wake cycles of athletes who had to perform in competitions that took place late at night.     

Food intake,conversion and swimming activity in the air-breathing catfish Heteropneustes fossilis

Summary Reared in tubular aquaria containing 20, 40 and 60 cm depth 0f water, Heteropneustes fossilis (20 g; 17 cm body length), an air-breathing catfish, swam 40, 80 and 120 cm/surfacing to exchange atmospheric air. With decreasing Po₂, the starving groups reduced the surfacing, whereas, the decrease in the Po₂ beyond 70 mm Hg induced the feeding groups to surface more frequently. Feeding groups exposed to 20 and 40 cm depth surfaced 353 and 423 times, travelling distances of 141 and 338 m/day, at the energy cost of 8.5 and 9.7 mg dry fish substance/g live fish/day, respectively. The corresponding starving groups surfaced only 163 times/ day and swam 65 and 130 m/day at the expense of 1.2 and 1.6 mg/g/day. Feeding and starving groups reduced the number of surfacing, when the distance they have to swim exceeded 0.8 m/day and increased the proportion of O₂ taken up branchially; the starving and feeding groups exposed to 60 cm depth surfaced only 70 and 271 times, swimming 84 and 325 m/day, at the energy cost of 2.9 and 17.6 mg/g/day. Feeding and conversion rates steadily increased from 16.9 mg dry liver/g live fish/day and 6.7 mg dry fish substance/g live fish/day in those exposed to the shallowest aquarium to 27.4 mg/g/day and 7.0 mg/g/day in those exposed t0 the maximum depth, respectively; conversion efficiency was 44% in the former and 28% in the latter; hence culturing H. fossilis in the shallow waters is profitable.     

Age,seasonal and diel variations of the uricolytic enzymatic system in the snailsXeropicta arenosa (Ziegler) andCernuella virgata (Da Costa)

Summary The nitrogen catabolism of two snail species,Xeropicta arenosa andCermuella virgata, living on coastal dunes, was studied at different seasons and times of the day and at different ages. All the nitrogenous metabolites of the uricolytic enzymatic system were found in body homogenates of the snails, although uric acid was most abundant. The highest levels of these catabolites were observed during the day when the snails were inactive, while the lowest levels occurred during the night when excretion probably took place. The levels of most of the nitrogenous catabolites and the activities of the enzymes were higher in juveniles than in adults.All the enzymes of the uricolytic pathway were shown to be present in bothX. arenosa andC. virgata.     

Morphological responses to different flooding regimes in Carex brevicuspis

Water regime can be described by the depth, duration, frequency, and timing and predictability of flooded and dry phases. Despite growing recognition of the importance of water regimes in the regulation of plant growth and distribution, which components of water regimes that determine plant growth are not well known. To identify the causative components, 72 ramets of Carex brevicuspis were grown under six different water regime treatments (treatment A: constant 0 cm water level; treatment B: constant 30 cm water level; treatment C: 0 cm water level to 30 cm water level for 30 days, repeated 2 times; treatment D: 30 cm water level to 0 cm water level for 30 days, repeated 2 times; treatment E: 0 cm water level to 30 cm water level for 5 days, repeated 12 times; and treatment F: 30 cm water level to 0 cm water level for 5 days, repeated 12 times). Biomass accumulation, below:above ground biomass ratio, number of ramets, and proportions of spreading and clumping ramet were assessed. Biomass accumulation decreased only in relation to length of flooding. The highest biomass accumulation occurred in the 120‐day + 0 cm water level treatment, it was intermediate in the four 60 day + 30 cm water level treatments, and lowest in the 120 day + 30 cm water level treatment. Likewise, the below:above ground ratio decreased only with increasing length of flooding. Ramet number was highest in the 120 day + 0 cm water level treatment, intermediate in the four 60 day + 30 cm water level treatments, and lowest in the 120 day + 30 cm water level treatment. The proportion of spreading ramets increased from 28.0% in the 120 day + 0 cm water level treatment to 76.4% in the 120 day + 30 cm water level treatment. These data suggest that the growth of C. brevicuspis was only limited by the duration of flooding. Reduction of the below:above ground ratio and change from phalanx to guerrilla growth form are effective strategies for C. brevicuspis to acclimate to flooding stress, because they allow the plant to grow above the water surface and escape from anoxic conditions. Our study provides experimental information on the role of different components of water regimes in regulating plant growth, and may assist in protection and restoration of the C. brevicuspis community.     

Reproductive under-performance of tsetse flies in the laboratory, related to feeding frequency

Abstract. The rates of development of the eggs and larvae in utero and the next two developing ovarioles were measured by ovarian dissection on each day of the pregnancy cycle in tsetse, Glossina morsitans, subject to different feeding regimes. Compared with flies fed four times per pregnancy cycle, flies fed three times per cycle showed a lower pupal production rate (70%), the same (zero) adult mortality, a slightly slower growth rate of the larva and second ovariole only from day 8 onwards, but the same growth rate of the first ovariole. Flies fed only twice per pregnancy cycle produced no pupae, suffered 18% adult mortality and showed a significantly slower growth rate of the larva and second ovariole from days 6 and 7 respectively, but still the growth rate of the first ovariole was barely affected. Flies offered food three times or twice per pregnancy cycle engorged fully at every opportunity, but 16.5% of the flies offered food four times per cycle did not feed on every occasion, while 12–22% did not engorge fully on days 3, 5 or 7. In assessing the applicability of these laboratory results to the field situation the following points must be borne in mind: in the laboratory flies take smaller mean blood meals than in the field; during protein production associated with larval growth the proportion of the blood meal lost to transformation and excretory costs is less than during normal lipid metabolism; the balance between the tsetse's known fertility rate and adult and pupal mortality rates reveals that the abortion rate in the field must be extremely low. The high abortion rates usually observed in laboratory colonies, even when flies are offered food daily_l would be quite untenable in the field and indicate that laboratory conditions impose physiological stresses on the flies that are quite different from those in the field. These facts indicate that three field-sized meals may be sufficient to meet the energy demands of normal larval development in the field.     

Day length constrains the time budget of aphid predators

Phenology shifts and range expansions cause organisms to experience novel day length-temperature correlations.Depending on the temporal niche,organisms may benefit or suffer from changes in day length,thus potentially affecting phenological adaptation. We assessed the impact of day length changes on larvae of Chrysoperla carnea (Stephens) and Episyrphus balteatus (De Geer),both of which prey on aphids.Larvae ofE.balteatus are night-active,whereas those of C.carnea appear to be crepuscular.We subjected both species in climate chambers to day lengths of 16 :8 L :D and,to circumvent diapause responses,20 :4 L :D.We recorded development times and predation rates of both species. E.balteatus grew 13%faster in the 16 :8 L :D treatment and preyed on significantly more aphids.In contrast,C.carnea grew 13% faster in the 20 :4 L :D treatment and higher predation rates in 20 :4 L :D were marginally significant.Our results show that day length affects development and predation,but that the direction depends on species. Such differences in the use of day length may alter the efficiency ofbiocontrol agents in a changing climate.     

Histological study on the chronology of the developing dentition in gorilla and orangutan

The single previous study on tooth development in great apes (Dean and Wood: Folia Primatol. (Basel) 36:111–127, 1981) is of limited value because it is based on cross-sectional radiographic data. This study considers problems in defining stages of tooth development in radiographs of developing ape dentitions and provides data on tooth chronology in Pongo pygmaeus and Gorilla gorilla by using histological methods of analysis. Crown formation times were estimated in individual teeth, and an overall chronology of dental development was found by registering teeth forming at the same time by using incremental growth lines. The earlier radiographic study correctly identified the molar and second premolar chronology and sequence in great apes, but significantly underestimated crown formation times in incisors, first premolars, and canine teeth in particular. Ape anterior tooth crowns take longer to form than the equivalent human teeth, but the overall dental developmental period in great apes is substantially shorter than in humans. Gorilla root extension rates appear to be fast, up to approximately 13 μm/day. This rapid root growth, associated with early tooth eruption, appears to be the developmental basis for the observed differences in timing between developing dentitions in great apes and humans.     

Circadian rhythm does not affect responses to chemical cues in the red swamp crayfish,Procambarus clarkii

Studies of crayfish chemical ecology have been conducted in both day and night conditions. This variation may hinder the comparison of data among studies, if the responses by crayfish to chemical cues are dependent upon the time at which the cues are encountered. We tested the hypothesis that responses to chemical cues are dependent on observation time using the red swamp crayfish, Procambarus clarkii. Procambarus clarkii is known to exhibit a light-regulated circadian rhythm, with nocturnal activity peaks. Habitat use differed significantly between non-stimulated periods and periods of exposure to a food stimulus, but no effects of photoperiod (normal vs. reversed) or laboratory conditions (dark vs. light) were observed. The results suggest that, all else being equal, (1) studies of crayfish chemical ecology can be successfully conducted in a variety of experimental conditions, and (2) previous studies conducted at various times of the day should have comparable results.     

Development Times Under Long- and Short-Day Conditions in the Kanzawa Spider Mite <Emphasis Type="Italic">Tetranychus kanzawai</Emphasis> (Acari: Tetranychidae)

In a theoretical framework, the development time of arthropods is closely associated with population growth, so that strong selection pressure may be imposed on development patterns. In this context, selection towards shorter development times may act on female mites in the season when population size is growing. In contrast, such selective pressure may be weaker just before hibernation, because the stage adjustment may be more important than population growth in such seasons. Thus, selection to shorten development times may act more strongly in long daylength conditions, so that different developmental responses among the seasons (reaction norm) may evolve. I predicted that the development time is shorter under the long-day conditions of population-growing seasons than under the short-day conditions of hibernating seasons, and that genetic variation at the long-day is smaller than that at the short-day. In order to test this prediction, the egg-to-adult development time of a population of Tetranychus kanzawai (Acari: Tetranychidae) was investigated under short (9L:15D) and long (15L:9D) daylength conditions at 18 °C. In addition, genetic variation in female development times under these conditions was estimated by using half-sib design. The development time of females at short day was 1 day longer than at long day under the experimental conditions. Male development times follow the pattern of females with <1 day delay. However, heritabilities under these two treatments were quite low and neither was significant. Thus, only the first prediction was supported by the results. In addition, maternal and/or non-additive effects in the female development time were highly significant under both daylength conditions examined.     

Activity of Acetylcholinesterase in the Motor-Sensory Cortex in Early Ontogenesis of Rats Exposed to Prenatal Hypoxia

Effects of acute prenatal hypoxia (13–14 days of gestation, 3 h, O₂ = 7%) on acetylcholinesterase (AChE, EC 3.1.1.7) activity in homogenates, synaptosomes, and cytosol of the motor-sensory cortex of Wistar rats were studied on the days 1, 5, 10, 19 and 30 after birth. In homogenates of normally developing cortex, the AChE activity did not significantly change with age. Activity of AChE in synaptosomes increased 4 times throughout the entire period of observation, while in the cytosol, 4.3 times to reach maximum at the 19th day. Maximum rise of the AChE activity in synaptosomes was observed at the period from the 5th to the 10th day. Activity of AChE in homogenate and synaptosomes of rats submitted to prenatal hypoxia decreased during the first five days after birth (p < 0.001) but later, starting from the day 10, it increased in all fractions. A statistically significantly higher activity of AChE than in controls was revealed in homogenate of the motor-sensory cortex on day 19 (p < 0.01), while in synaptosomes, on the days 19 and 26 (p < 0.001 and p < 0.05, respectively), and in cytosol, on the days 10, 26, and 30 (p < 0.05, p < 0.05, and p < 0.001). Maximum change in the ratio of AChE activities in cytosol and synaptosomes was found on the day 19 (p < 0.01). At the same period of development, changes in the ratio of AChE activity in synaptosomes and homogenate of the control and hypoxic animals were also observed. Thus, prenatal hypoxia leads to in changes in the activity both of the cytosol and synaptosomal membrane-bound forms of AChE in the motor-sensory cortex of rats, which agrees with our own and literature data on disorder of neuro- and neuritogenesis in the process of formation of CNS and of behavioral reactions in early postnatal ontogenesis under the effect of pathogenic factors at certain days of prenatal ontogenesis.     

Pilot studies to identify the optimum duration of concomitant Helicobacter pylori eradication therapy in Thailand

Background and Aim: Eradication rate for Helicobacter pylori infection with standard triple therapy has globally declined including in Thailand, and new regimens are required that provide reliable high eradication rates. The study was designed to determine whether concomitant therapy administered for either 5 or 10 days would produce a ≥ 95% (grade A) treatment success in H. pylori infected Thai subjects with nonulcer dyspepsia. Methods: Two prospective, but separate, pilot single‐center studies were carried out during September 2009–December 2010 at Thammasat University Hospital, Thailand. H. pylori infected subjects were randomized into the two pilot studies; either 5‐day or 10‐day concomitant therapy. Thai concomitant therapy consisted of rabeprazole (20 mg) twice daily, amoxicillin 1 g twice daily, metronidazole 400 mg three times a day, and clarithromycin MR 1 g once daily. H. pylori status was assessed by ¹³C‐urea breath test 4 weeks after completion of the treatment. Successful treatment was defined as achieving a grade A result (≥95%) and failure by <90% cured. Results: A total of 110 subjects were randomized (55 to the 5‐day treatment trial and 55 to the 10‐day regimen). Baseline subject demographic and clinical characteristics were similar in both studies. All subjects completed their assigned therapies. The 10‐day concomitant treatment trial was successful in 53 of the 55 subjects (96.4%; 95% CI 87.4–99.5%). The 5‐day concomitant pilot was judged to be a failure as only 49 of 55 subjects (89.1%; 95% CI = 77.7–95.8%) were cured. The frequency of adverse events was low and similar in the two studies. Conclusion: The 10‐day concomitant regimen provided excellent treatment success (eradication rate >95%) and was well tolerated. Ten‐day concomitant therapy is likely to become useful first‐line H. pylori eradication in Thailand.     

Physical activity intensity and risk of overweight and adiposity in children

Background: Physical activity recommendations for children focus on duration of activity and underemphasize intensity. Objective: To evaluate the relationship between physical activity (intensity and duration) and the odds of being overweight, >20% body fat and >25% body fat. Methods and Procedures: Body fat, BMI and physical activity (accelerometry) were measured in children (n = 251) aged 8–10 years. Physical activity was quantified as time in moderate physical activity (MPA) and vigorous physical activity (VPA). Results: Prevalence of overweight and obesity were 18 and 11.6%, respectively. Regression indicated that VPA, not MPA, is associated with body fat (r = 0.35, P < 0.001) and BMI (r = 0.26, P < 0.001). Odds ratio demonstrated a significant impact of MPA and VPA on body composition. Children performing ≤ 5 min/day of VPA are 4.0 times more likely to have ≥ 20% body fat (P < 0.001), 2.9 times more likely to have ≥ 25% body fat (P < 0.05) and 5.2 times more likely to be classified as overweight (P < 0.01) compared to children performing ≥ 15 min/day. Those performing ≤ 15 min/day of MPA vs. >45 min/day MPA are at 4.2 increased odds of having ≥ 20% body fat (P < 0.001), and 3.0 increased odds of having ≥ 25% (P < 0.01). Discussion: Lower durations of both MPA and VPA are associated with increased odds of overweight and adiposity. Forty‐five minutes of MPA and fifteen minutes of VPA were associated with reduced body fat and BMI. We recommend that these amounts are used to develop minimum physical activity intensity guidelines for the prevention and treatment of obesity.     

The effect of biochanin A on the chlorophylls and carotenoids content in the alga <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> Beijerinck

The present study was undertaken to determine the influence of biochanin A, isoflavone characterised by estrogenic activity, upon the content of chlorophylls and carotenoids in the cells of green alga Chlorella vulgaris Beijerinck (Chlorophyceae). On the 6^th day of cultivation under the influence of 10⁻⁶ M biochanin A exerted the greatest biological activity and the most stimulating effect on the analysed parameters: growth of the alga expressed by the cells number and the content of photosynthetic pigments in them. The total content of carotenoids was stimulated on the 6^th day of experiment in the range of 197 % but during the 9^th day only in 179 % in comparision with the control group (100 %). At the same time content of carotenes increased to the level of 123 – 119 % and xanthophylls to 208 – 178 %. Among the carotenes, β-carotene was characterised with the 3.7 times higher content in regard to the content of α-carotene on the 6^th day of cultivation and during the 9^th day — the 5.7 times domination. The content of xanthophylls that contain two atoms of oxygene in molecule (oxygen — poor xanthophylls) was intensively stimulated in the range of 224 %. Moreover, the oxygen — rich xanthophylls content reached the value 179 % when compared to the control. The greatest stimulation of the content of chlorophylls and its isomers was observed during the 3^rd day of cultivation of Chlorella vulgaris when it rose up to 166 % and to 156 % on the 6^th day. The content of chlorophyll b and its isomers was stimulated in 181 % on the 6^th day of culture and 155 % during the 9^th day of algal culture. The evidence on the stimulating effect of biochanin A as the main representative of isoflavones on the growth and content photosynthetic pigments in eucaryotic alga C. vulgaris was demonstrated in these studies.     

长江口盐沼植被生境内斑尾刺虾虎鱼食性特征

根据2015年5月至2016年4月在长江口东滩盐沼湿地水域采集的斑尾刺虾虎鱼样本数据,分析了该生境斑尾刺虾虎鱼的生物学和食性特征。结果表明:共采集到斑尾刺虾虎鱼186尾,其中6—8月采集的数量较高,而其他月份较低。约96%个体为幼体(平均体长109 mm),平均摄食等级为1.5。斑尾刺虾虎鱼主要摄食虾类(IRI(%)=69.05)、鱼类(IRI(%)=17.31)、蟹类(IRI(%)=11.51)和双壳类(IRI(%)=0.95)等11大类41小类饵料生物;虾类作为最重要的饵料类别,其生物量、数量和出现频次百分比均排列第一,以安氏白虾(Exopalaemon annandalei)、日本沼虾Macrobrachium nipponense)、长额刺糠虾(Acanthomysis longirostris)等虾类为主要饵料。鱼类饵料中,以大鳍弹涂鱼(Periophthalmus magnuspinnatus)、大弹涂鱼(Boleophthalmus valenciennes)等虾虎鱼科鱼类为主要饵料。各月平均饱满指数P(%)波动较大,6—11月呈逐渐增加趋势。随着体长的增加,饵料组成中鱼类的比例呈逐渐增高趋势,成体个体的饵料中鱼类的生物量比例达65%以上,虾类的比例则下降明显。6—8月斑尾刺虾虎鱼白天样本中鱼类饵料的重量百分比显著高于夜晚(P0.01),约是夜晚的8倍;但虾类则是夜晚显著高于白天(P0.01),约是白天的2倍,而蟹类饵料的昼夜差异不显著。从等级聚类(即组平均法)的分类方法可知,斑尾刺虾虎鱼各体长组食物组成在10%相似性水平上可分为3类,即41—60、61—180 mm和181—200 mm。从营养生态位宽度来看,41—60 mm体长组生态位宽度值为0.86,而61—120 mm体长组随着体长的增大而增大,但121—160 mm体长组生态位有所降低。盐沼生境丰富的饵料环境为斑尾刺虾虎鱼提供了良好的摄食场所,同时盐沼植被茂密的植株也可为幼体提供躲避捕食者的最佳庇护所,初步证明盐沼对于斑尾刺虾虎鱼具有重要的生境价值。     

Levels of diurnal predation on a school of flat-iron herring,Harengula thrissina

Synopsis The incidence of diurnal predation (0800–1600h) on schools of several hundred thousand adult flat-iron herring,Harengula thrissina, was quantified. Nine species of piscine predators perpetrated 653 attacks and 158 captures during 42.5 h of observation. Four predators: cabrilla,Mycteroperca rosacea, cornetfish,Fistularia commersonii, green jack,Caranx caballus, and black skipjack,Euthynnus lineatus, were responsible for 92% of the attacks and 96% of the successes. Among these predators attack rates (attacks × time^–1) and success rates (successes × attacks^–1) varied with respect to time of day, although all predators were active throughout the day. As a consequence, the herring school experienced fairly homogeneous attack and success rates. These rates were estimated as roughly half the crepuscular attack rates but they were sustained over a much longer period. Piscivorous predators, particularly those species frequently found in association with schooling prey, may be focusing their attacks on opportunities, not specific times of day and/or light levels. More direct information needs to be gathered on diurnal as well as crepuscular attack and success rates in order to assess the impact that piscine predators have on schooling prey.     

Field evaluation of oxygen consumption by two freshwater decapod morphotypes (Trichodactylidae and Aeglidae); the effect of different times of the day,body weight and sex

We report an analysis of the effect of two different times of day (noon and dusk), body weight and sex on the oxygen consumption rate (OCR) of the freshwater crabs Trichodactylus kensleyi (Trichodactylidae), Aegla singularis and A. platensis (Aeglidae) in their natural environment. Both families are sympatric in the studied locations, with a co-occurrence found between T. kensleyi and A. singularis or T. kensleyi and A. platensis. The mean OCR was highest in A. singularis and lowest in A. platensis. The OCR was higher in Aegla species at noon, and Trichodactylus consumed more oxygen at dusk. In aeglids, there was no difference in oxygen consumption between noon and dusk. T. kensleyi exhibited statistically significant differences in the OCR between noon and dusk. The oxygen uptake of all three species analysed was not influenced by the sex of the individual but varied according to the animals’ weight. The families evaluated share some biological and ecological characteristics, such as diet and habitats, but the strategies used in the regulation of gas exchange at different times of the day were different. Environmental factors may be influencing the oxygen consumption of each morphotype differently.     

Age at reproductive maturity and effect of age and time of day on sex attraction in the potato psyllid Bactericera cockerelli

Abstract The potato psyllid, Bactericera (= Paratrioza) cockerelli (?ulc) (Hemiptera: Triozidae), is a major pest of potato. Studies were conducted to determine the age at which both males and females reach reproductive maturity and the effect of age and time of day on sex attraction. Adult B. cockerelli reach reproductive maturity within 48 h post‐eclosion, with females being mature on the day of eclosion and males at 1 day post‐eclosion. Oviposition generally began 2 days after mating but was delayed when females mated within 2 days post‐eclosion. In laboratory olfactometer assays, the age of females used as odor sources and the age of males assayed to these odors did not affect sex attraction, with both younger (1–4‐day‐old) and older (8–10‐day‐old) males being attracted to females, regardless of female age (1–4‐day‐old or 8–10‐day‐old). Males assayed to live females at different times during the photophase (between 8:00 and 20:00 hours) were attracted to females between 11:00 and 17:00 hours, showing a temporal periodicity in sex attraction with B. cockerelli at least during the photophase.     

Effects of feeding and starvation on growth and swimming activity in an obligatory air-breathing fish

Reared in (tubular) aquaria containing different depths of water, Ophiocephalus striatus (0.7 g, 4.5 cm body length), an obligatory air-breathing tropical fish, swam long or short distances to enable themselves to exchange atmospheric air. In each tested depth (2.5, 5.0, 15.5, 31.0 and 40.0 cm) series, one group was starved, while the other was fed ad libitum twice a day on fish muscle. In the shallowest water (2.5 cm depth), the feeding group surfaced 1,294 times, travelling 64.7 m at an energy cost of 20.4 mg dry fish substance/g live fish/day, against those exposed to the deepest water (40 cm depth), which expended 35.8 mg/g/day, swimming 1,503.4 m on 1,879 visits to the surface. The starving group surfaced only 482 times, travelling 24.1 m at an expense of 5.8 mg/g/day in the shallowest water, while those at 40 cm depth surfaced 504 times, swimming 403.2 m at an energy cost of 7.4 mg/g/day. Owing to the sustained swimming activity and the consequent fatigue, the test individuals belonging to both groups in all the tested series hang to the surface for a definite interval, repaying the O₂ debt. Observations were also made to assess the duration of hanging to precisely estimate the distance travelled. Irrespective of changes in depths of water, the duration of hanging to surface was only 3.0 hr/day for the feeding groups, while it was as much as 15.5 hr/day for the starving groups. The maximum sustained metabolic level of O.striatus reared in 40 cm depth was equivalent to 1.23 ml O₂/g/hr, which is about 2 times higher than the value reported for the active metabolism of swimming Oncorhynchus nerka at 15°C in Brett's (1964) respirometer. O.striatus reared in 2.5 cm depth fed 32.0 mg and converted 6.7 mg dry food/g live fish/day, while those exposed to the deepest water fed 49.1 mg, but converted only 5.5 mg/g/day. Culturing obligatory air-breathing fishes in shallow waters will be advantageous.     

The changes in the antioxidant status of heart during experimental hypomagnesemia in balb/c mice

The present experiment was performed to assess if hypomagnesemia can influence antioxidant status in mice heart. The results could explain possibly a free radical theory of heart damage in magnesium deficiency. We used a rodent model of hypomagnesemia. The magnesium sufficient group received a standard diet whereas a magnesium deficient group received the diet containing a trace amount of magnesium. The activities of the most important antioxidant enzymes – catalase, glutathione peroxidase and superoxide dismutase were assessed in mice heart and liver in a time dependent manner, on the 10th and the 20th day of experiment. The level of magnesium in plasma of animals receiving the magnesium deficient diet dropped twice after the 8th day and four times after the 13th day and then reached a plateau value. The activity of catalase in heart in the magnesium deficient group increased gradually and was significantly (P<0.05) elevated by 27% on the 20th day of experiment whereas the superoxide dismutase activity was significantly decreased by 17% on the 20th day. Glutathione peroxidase activity was insignificantly elevated. The alterations of antioxidant enzyme activities in the heart indicate cardiomyocytes's exposure to oxidative stress, which can be responsible for the cardiac lesions observed during hypomagnesemia.