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Genetically based phenotype-environment association for swimming behavior in lake whitefish ecotypes (Coregonus clupeaformis Mitchill).

Studies of phenotype-environment associations in adaptive radiation have focused largely on morphological traits related to resource-based phenotypic differences. The genetic basis of adaptive behaviors implicated in population divergence remains poorly understood, as few studies have tested the hypothesis of behavioral phenotype-environment associations. We provide evidence of a phenotype-environment association for differential adaptive swimming behaviors through experiments conducted on dwarf, normal, and hybrid lake whitefish (Coregonus clupeaformis). Highly significant differences were observed for depth selection, directional changes, and burst swimming, implicating a genetic basis for these behaviors. Hybrid crosses revealed that depth selection is under additive genetic control, while dominance effects were suggested for directional changes and burst swimming. Estimates for the genetic basis of behavioral differentiation from an animal model were consistent with these observations. Comparative estimates of behavioral differentiation (Q(ST)) against neutral expectations (F(ST)) revealed pronounced departures from neutral expectations in all three behavioral phenotypes, consistent with the hypothesis that directional selection has driven the divergence of behavior in dwarf and normal lake whitefish ecotypes.

Animals↗

Swimming with a mastoid cavity: what are the risks?

The authors have found no studies and little guidance in the literature on the advisability of people swimming with a modified radical mastoid cavity. Two groups of such outpatients were therefore followed up at 2-monthly intervals for 6 months. One group of 56 patients swam (81% without ear protection) and the other group of 55 patients maintained their ears quite dry. Swimming did not increase the incidence of an infected mastoid cavity. The most important risk of swimming was vertigo which occurred in 5% of swimmers.

Adolescent↗

Swimming with earplugs: are they worthwhile?

The ears of 30 children were examined before and after swimming. Each ear was plugged with cotton wool which was then covered with petroleum jelly. Of the 60 earplugs, 4 (6.6%) were lost while swimming and water was seen in the ears. The remaining 56 (93.3%) earplugs were still in place after swimming. The plugs were removed and the ears, on otoscopy, were found to be dry. In a separate experiment with volunteers, water was instilled into 10 ear canals. Either 1 drop (0.05 ml), 2 drops (0.1 ml) or no water was instilled. Nine of the 10 ears were correctly judged to have either 'no water' or 'water present', suggesting that as little as 0.05 ml of water in an ear canal can be detected otoscopically.

Child↗

Water hygiene of two swimming pools: microbial indicators.

The microbiological quality of the water of two swimming pools was evaluated to determine which organisms might be the best indicators of pollution. Membrane filtration gave low numbers of the common indicators of faecal pollution but high counts of the indigenous skin bacteria. As illnesses normally contracted in a swimming pool are mostly those of the skin rather than intestinal, it is suggested that the best indicators of the hygienic condition of water in a swimming pool are staphylococci because of their resistance to disinfection, high numbers in the environment, and ease of recovery.

Bacteria↗

The relationships between fish health, metabolic rate, swimming performance and recovery in return-run sockeye salmon, Oncorhynchus nerka (Walbaum).

The repeat swimming ability and oxygen uptake (Mo2) of adult sockeye salmon, Oncorhynchus nerka (Walbaum), were assessed at ambient water temperatures at three field locations along their migration route. Following these measurements, internal and external fish condition was evaluated according to United States Environmental Protection Agency guidelines. Here we report on the physiological characteristics of fish having either moderate or severe levels of disease and injury. Routine oxygen uptake (Mo2) did not differ between healthy fish and those with indices of ill health. In contrast, fish classified as sick, which included conditions of damaged internal organs, an Ichthyophonus spp. heart infection, a Saprolegnia spp. gill infection, and skin wounds, had a lower post-exercise Mo2 and were unable to repeat their critical swim speed (U(crit)) on the second swim test. Moderate levels of disease or injury did not significantly affect either U(crit) or post-exercise Mo2. We conclude that the ability of adult salmon to recover quickly from exercise may be a useful indicator of sublethal pathologies.

Animal Migration↗

Swimming pool attendance and hay fever rates later in life.

BACKGROUND: Exposure to chlorination by-products through swimming pool attendance showed adverse health effects on children. The aim of our study was to assess whether pool attendance in childhood would be related to higher rates of allergic diseases in adulthood, with special regard to hay fever. METHODS: 2606 adults aged 35-74 years provided retrospectively collected information on swimming pool attendance and medical history, including data on atopic diseases. Information was assessed by a combination of a personal interview and a self-administered questionnaire. Logistic regression models were applied to study associations between hay fever and swimming pool attendance, adjusted for potentially relevant confounders, such as age, gender, region, education and smoking. RESULTS: Higher rates of hay fever could be seen when frequently exposed at school age (aOR: 1.74, 95% CI: 1.09-2.77), frequently exposed during the past 12 months (aOR: 1.32, 95% CI: 0.92-1.89) and ever exposed (aOR: 1.65, 95% CI: 0.98-2.78). Strongest associations were found for the youngest subjects and were dose-related to the extent of current and school-age pool attendance. CONCLUSIONS: Impaired integrity of the lung epithelial by exposure to chlorination by-products might facilitate a closer contact to allergens and therefore could result in higher rates of hay fever.

Adult↗

In vitro susceptibility of public indoor swimming pool fungi to three disinfectants.

The floors of indoor swimming pools are contaminated by yeasts, dermatophytes and other saprophytic species. Previous epidemiological studies have revealed that the fungi persist even after cleaning. Three disinfectants were tested in vitro against fungi standard isolated from swimming pool floors. Minimum inhibitory concentration (MIC) tests and AFNOR standard T72-201 were carried out. Adilon and Decalcite, commonly used in swimming pools, were ineffective against most of the fungi, while Nobactel, recommended elsewhere, was particularly effective against the studied fungi. In addition to the necessary technical modifications of the methods, this study highlights the need to choose effective antifungal compounds and to alternate cleaning products to minimize acquired resistance.

Arthrodermataceae↗

The influence of premotor interneuron populations on the frequency of the spinal pattern generator for swimming in Xenopus embryos: a simulation study.

Our aim was to test the hypothesis that the frequency of neuronal rhythm-generating networks is partly controlled by the size of the active premotor interneuron population. We have tested possible mechanisms for frequency changes in a population model of the Xenopus laevis embryo spinal rhythm-generating networks for swimming. After initiation by a brief sensory excitation, the frequency of swimming activity decreases to a steady level determined by the properties of the 24 interneurons and their connections. The initial frequency decrease was dependent on the time-course of initiating sensory synaptic excitation. When some premotor excitatory interneurons were given weaker synaptic connections to reflect the variability in the spinal cord, they could drop out and stop firing during the initial frequency decrease while swimming activity continued. If the synaptic input of such weak excitatory interneurons was graded finely, they could drop out consecutively. This led to further decreases in the level of tonic excitation and in network frequency which depended on the number, type and distribution of excitatory interneurons that stopped firing. Silent weak excitatory interneurons could be recruited by a second sensory excitation and cause an increase in tonic depolarization and frequency which outlasted the sensory input. Such recruitment could occur on both sides after local sensory stimulation to only one region or one side of the model. We conclude that these computer simulations support the hypothesis that premotor interneuron drop-out and recruitment is one mechanism which can control frequency in a locomotor central pattern generator.

Animals↗

Faecal pollution of ocean swimming pools and stormwater outlets in eastern Sydney.

We determined the levels of faecal contamination over a three-year period from 1991 to 1993 at selected ocean swimming pools and stormwater outlets to assess whether these levels represented a threat to public health. Three popular ocean swimming pools and three nearby stormwater outlets located in Sydney's eastern suburbs were included in the analysis. The ocean swimming pools consistently had elevated levels of faecal coliform bacteria; the highest microbe levels were observed in a pool used largely by children. Faecal coliform bacteria counts in the ocean pools at times reach levels likely to be associated with illness in bathers. Stormwater outlets at three locations had reducing counts over the three-year period. An improved system of sampling, testing and risk communication appears to be needed to reduce potential health risks to users of these popular ocean pools.

Colony Count, Microbial↗

An outbreak of cryptosporidiosis in an urban swimming pool: why are such outbreaks difficult to detect?

OBJECTIVE: To describe an outbreak of Cryptosporidium gastroenteritis in a swimming pool in Melbourne in early 1998 that was not detected through routine surveillance, and discuss difficulties in identifying such outbreaks. METHODS: The Water Quality Study (WQS) was a large community-based study of gastroenteritis. Following suspicion of an outbreak of cryptosporidiosis within the study group, due to pool "X", a nested case control study was performed. Each case of Cryptosporidium gastroenteritis was matched with six controls and data from weekly Health Diaries from the WQS were reviewed. The Department of Human Services also instigated active surveillance among patrons at pool "X" using a systematic sample of 50 people from the pool's swim-school enrollment list. RESULTS: There were seven cases of Cryptosporidium gastroenteritis in the case control study. Five cases and eight controls swam at pool "X" during the outbreak period. The adjusted odds of developing cryptosporidial diarrhoea if an individual swam at pool "X" was 34.5 (CI 2.3-2548). DHS identified another 11 laboratory confirmed cases associated with pool "X" as well as cases not linked to pool "X". 125 cases were identified throughout Melbourne with the suspected involvement of seven swimming pools. CONCLUSIONS: Despite a high odds ratio of developing cryptosporidiosis this outbreak was not detected by routine surveillance methods. Current outbreak detection methods lack sensitivity, specificity or timeliness. IMPLICATIONS: Improved surveillance systems are required if outbreaks of gastroenteritis are to be detected early so an intervention can be instigated to reduce the amount of subsequent illness.

Animals↗

Longitudinal distribution of components of excitatory synaptic input to motoneurones during swimming in young Xenopus tadpoles: experiments with antagonists.

1. Recent studies have revealed that the excitatory synaptic input to spinal motoneurones during fictive swimming in Xenopus tadpoles has three main components: glutamatergic (Glu) from premotor excitatory interneurones, nicotinic cholinergic (nACh) from more rostral motoneurones, and electrotonic coupling from neighbouring motoneurones. During swimming, these components sum to produce two kinds of excitation: phasic excitation (EPSPs) underlying spikes, and tonic depolarization. 2. We have investigated the longitudinal distribution of these excitatory synaptic inputs to presumed motoneurones at different positions along the spinal cord using intracellular recording techniques. Different antagonists (10 microM dihydro-beta-erythroidine (DHbetaE) for nicotinic ACh receptors (nAChRs), 2 mM kynurenate (Kyn) for glutamate receptors (GluRs), and 100 microM Cd2+ for all chemical synapses) were microperfused very locally to unmask the relative contributions of these components to the total excitatory drive, and their distribution along the spinal cord during swimming. 3. If the potentials remaining when all chemical components were blocked by Cd2+ were subtracted from potentials recorded after blocking nAChRs and GluRs with DHbetaE plus Kyn, a small unidentified component was observed. This component was blocked by the specific AMPA antagonist 6-nitro-7-sulphamoylbenzo(f)quinoxaline-2,3-dione (NBQX, 5 microM), so is glutamate mediated. 4. We used the potential measurements to calculate the relative synaptic conductances of the different synaptic inputs, and conclude that: (a) there is a rostral-caudal gradient in input during EPSPs and tonic depolarization; (b) the glutamatergic component accounts for most of the excitation, and decreases caudally; (c) cholinergic and electrotonic components are relatively constant in different positions along the spinal cord; and (d) these two components provide an increasing proportion of the input in more caudal neurones. 5. We propose that the glutamate components of excitation are fundamental to rhythm generation in the brainstem and rostral cord, while the electrotonic and cholinergic components ensure that the central pattern generator activates motoneurones effectively in all parts of the spinal cord.

Animals↗

Sex differences in the effects of acute swim stress on binding to GABAA receptors in mouse brain.

Acute swim stress (3-min swim at 32 degrees C) in female, but not in male, mice results in substantial changes in the characteristics of GABA binding to membranes prepared from the forebrain. These changes were larger when measured in a relatively crude membrane preparation than in a well-washed membrane preparation commonly used in GABA binding assays, consistent with the loss of endogenous modulators of GABA binding in the latter preparation. These changes may be related to stress-induced alterations in part in the modulation of the characteristics of GABA binding by endogenous steroids, as the acute swim stress produced a larger increase in plasma corticosterone levels in female than in male mice.

Analysis of Variance↗

Noradrenaline release in rats during prolonged cold-stress and repeated swim-stress.

1 Plasma noradrenaline concentration in rats was measured during prolonged cold-stress and repeated swim-stress. 2 Cold exposure for 6 h caused a rise in plasma noradrenaline which reached a peak at 4 h. 3 Administration of desmethylimipramine and normetanephrine to block neuronal and extra-neuronal uptake of noradrenaline raised plasma noradrenaline concentration without changing the pattern of the response to cold exposure. 4 Repeated cold exposure on subsequent days produced no change in the pattern of plasma noradrenaline concentration. 5 Five successive 1-min swims at 30-min intervals caused a rise in plasma noradrenaline concentration which was maximal after the third swim. 6 It is suggested that prolonged and repeated activation of sympathetic nerve terminals leads to a decline in noradrenaline release.

Animals↗

The antidepressant-like effect of the melatonin receptor ligand luzindole in mice during forced swimming requires expression of MT2 but not MT1 melatonin receptors.

We previously reported an antidepressant-like effect in C3H/HeN mice during the forced swimming test (FST) following treatment with the MT1/MT2 melatonin receptor ligand, luzindole. This study investigated the role melatonin receptors (MT1 and/or MT2) may play in the effect of luzindole in the FST using C3H/HeN mice with a genetic deletion of either MT1 (MT1KO) or MT2 (MT2KO) melatonin receptors. In the light phase (ZT 9-11), luzindole (30 mg/kg, i.p.) significantly decreased immobility during swimming in both wild type (WT) (135.6 +/- 25.3 s, n = 7) and MT(1)KO (132.6 +/- 13.3 s, n = 8) as compared with vehicle-treated mice (WT: 207.1 +/- 6.0 s, n = 7; MT1KO: 209.5 +/- 6.2 s, n = 8) (P < 0.001). In the dark phase (ZT 20-22), luzindole also decreased time of immobility in both WT (89.5 +/- 13.9 s, n = 8) and MT1KO (66.5 +/- 6.4 s, n = 8) mice as compared with the vehicle treated (WT: 193.8 +/- 3.5, n = 6; MT1KO: 176.6 +/- 6.2 s, n = 8) (P < 0.001). Genetic disruption of the MT1 gene did not alter the diurnal rhythm of serum melatonin in MT1KO mice (ZT 9-11: 1.3 +/- 0.6 pg/mL, n = 7; ZT 20-22: 10.3 +/- 1.1 pg/mL, n = 8) as compared with WT (ZT 9-11: 1.4 +/- 0.7 pg/mL; ZT 20-22: 10.6 pg/mL). Swimming did not alter the serum melatonin diurnal rhythm in WT and MT1KO mice. Decreases in immobility of WT and MT1KO mice by luzindole treatment were not affected by gender or age (3 months versus 8 months). In contrast, luzindole did not decrease immobility during the FST in MT2KO mice. We conclude that the antidepressant-like effect of luzindole may be mediated through blockade of MT2 rather than MT1 melatonin receptors.

Animals↗

Is swimming exercise or cold exposure for rats?

Rats were trained by daily swimming sessions (up to 3 h per day) for at least 6 weeks in water at 30, 36 and 38 degrees C. After this training, the adaptive changes obtained were compared with those typical of cold-acclimated (cold-specific changes) and running-trained (training-specific changes) rats. The most typical training-specific change, an increased activity of oxidative muscle enzymes was negligible for swimming-trained rats, while the lowered activity of muscle lactate dehydrogenase was evident for all trained groups. Cold-specific changes, such as increased food intake, increased calorigenic response to injected noradrenaline, an increase both in mass and metabolic capacity of brown adipose tissue, and maintenance of the stores of ascorbic acid and muscle glycogen during cold exposure, were observed for rats trained at 36 and 30 degrees C. The cold tolerance test in cold air did not make any distinct difference between the rats trained at different water temperatures, while in cool water the 30 degrees C -swimmers were clearly superior to other groups, that is, their cooling rate was slowest. Other adaptive changes were found, to a variable extent, for all trained groups. These included loss of body fat, cardiac hypertrophy, reduced urinary catecholamine excretion after test swimmings either in cold or warm water, increased tail-skin temperature response to isoprenaline, and a higher tail-skin temperature in response to cold. Generally, however, the adaptive changes observed for 30- and 36 degrees C-swimmers were similar, while the changes observed for 38 degrees C-swimmers were different. The latter group neither displayed any cardiac enlargement nor any cold-specific changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

Lack of effects of handling habituation and swimming stress on ethanol-induced motor impairment and GABAA receptor function.

The effects of handling habituation and swimming stress on ethanol-induced motor impairment and the GABAA receptor function were studied in adult male Wistar rats. Daily handling for 3 to 5 weeks had no significant effect on ethanol-induced motor impairment in the tilting plane test or on the activity of the rats in the elevated plus-maze test of anxiety. Plasma corticosterone concentrations were greatly elevated by the tilting plane test procedure, irrespective of handling habituation. Acute, 10-min swimming stress at +25 degrees C produced an elevated plasma corticosterone concentration comparable to that produced by the tilting plane test, again irrespective of handling habituation. In cerebrocortical homogenates, short-term swimming stress had no statistically significant effect on the muscimol stimulation of the GABAA receptor-mediated 36Cl- flux in handled and non-handled animals. Thus, handling habituation and stress had only minor effects on the activity of the central GABAergic systems in acute tests at behavioural and biochemical levels.

Animals↗

Neuromodulation intrinsic to the central pattern generator for escape swimming in Tritonia.

Extrinsic neuromodulatory inputs to central pattern generators (CPGs) can alter the properties and synaptic interactions of neurons in those circuits and thereby modify the output of the CPG. Recent work in a number of systems has now demonstrated that neurons intrinsic to CPG can also evoke neuromodulatory actions on other members of the CPG. Such "intrinsic neuromodulation" plays a role in controlling the CPG underlying the escape swim response of the nudibrach mollusc, Tritonia diomedea. The dorsal swim interneurons (DSIs) are a bilaterally represented set of three serotonergic neurons that participate in the generation of the rhythmic swim motor program. Serotonin released from these CPG neurons functions both as a fast neurotransmitter and as a slower neuromodulator. In its modulatory role, serotonin enhances the release of neurotransmitter from another CPG neuron, C2, and also increases C2 excitability by decreasing spike frequency adaptation. These neuromodulatory actions intrinsic to the CPG may be important for the initial self-configuration of the system into a function CPG and for experience-dependent changes in the output such as behavioral sensitization and habituation.

Animals↗

Postnatal cocaine exposure: effects on behavior of rats in forced swim test.

Exposure to cocaine in early periods of postnatal life has adverse effects on behavior, namely, it induces the display of anxiety and fear-like behaviors that are associated with stress and depression. This study examined the effects of early developmental cocaine exposure in several categories of behavior observed in forced swim test. Male and female Wistar rats were given 15 mg/kg of cocaine hydrochloride/body weight/day, subcutaneously, in two daily doses, from postnatal day (PND) 1 to PND27. Controls were saline injected in the same protocol. In PND26-PND27, rats were placed in a swimming pool during 5 min in two sessions. The categories of behavior studied in this work included horizontal and vertical rotation, vibrissae clean, head clean, fast and slow swim, struggling, floating, sliding, diving, head-diving, and wagging head. Results showed differences in the frequencies of several behavioral categories that allowed the discrimination of the behaviors that may constitute "behavioral despair" indicators, as well as which behaviors are most affected by cocaine exposure. Cocaine groups were less active and more immobile than controls. These results suggest that postnatal exposure to cocaine can produce depression-like effects and affect the ability of these animals to cope with stress situations.

Aging↗