首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
SYNOPSIS. Monocercomonas molae from the hindgut of the sunfish Mola mola is described. The host was taken from southern California coastal waters in October, 1964. The body of the flagellate is 8.0 × 10.7 microns. A single basal granule complex gives rise to 4 flagella, one of which is recurrent. The axostyle is relatively stout, with argentophilic granules, and possesses a periaxostylar ring. The capitulum of the axostyle continues into the sickle-shaped pelta, and the parabasal body is rod-shaped or lobed and roughly triangular in cross-section.  相似文献   

2.
3.
The ocean sunfish Mola mola is considered to be globally distributed in both temperate and tropical waters, but there are many gaps in the knowledge of this species' distribution. A total of 31 records of M. mola from Icelandic waters, dating from 1845 to 2014, are presented and georeferenced. An increase in the number of records at the beginning of this century and particularly in 2012, is suggested to be a consequence of both an increase in ocean temperature on the Icelandic shelf and changes in large scale temperature variations in the North Atlantic Ocean.  相似文献   

4.
The cosmopolitan opah Lampris immaculatus (also known as the moonfish or mariposa) occurs commonly in New Zealand waters. The otoliths of 23 individuals were examined by light microscopy. All three of the otoliths of the endolymphatic sac of the opah have the characteristic appearance of the Stolkowski crystal form of the vaterite morph of calcium carbonate. Five randomly chosen pairs of asterici and sagittae and two lapilli otoliths were shown by X-ray diffraction to be composed of vaterite. In addition to their mineral composition, the sagitta and astericus of the opah present an unusual combination of anatomical features found in both what are generally regarded as primitive and as advanced fish. Vaterite otoliths also occur in the sunfish Mola mola and M. ramsayi, but with a different crystalline habit to that found in the opah, and in a distinctively different anatomical arrangement of the endolymphatic sac. It is argued that, based on their otolith mineralogy and morphology, the opah and the sunfish are each side of one of the biochemical and anatomical boundaries involved in the separation of the teleosts from other actinopterygian fish (sturgeons, paddle fish, gars and bowfins).  相似文献   

5.
Between September 2006 and April 2007 the authors transported one 0.9 m wingspan Mobula mobular from Olhão (South of Portugal) to Valencia (East of Spain), 12 ∼1.0 m long Argyrosomus regius to Tarragona (Northeast of Spain) and four ∼0.4 m long Mola mola to Atlanta (GA, USA). These journeys had a total “water to water” duration of 17, 22 and 33 hr, respectively. The first two transports were conducted by road whereas the third involved a combination of road and air travel. Water quality parameters—specifically dissolved oxygen, temperature, pH and ammonia—were monitored continuously throughout the duration of the trips and were maintained at optimum levels through the use of battery‐powered filtration and chemical supplements. All animals arrived alive and well at their destinations. This paper reports on the specific transport regime adopted in each case and provides some insight for potential improvements in future similar transports. Zoo Biol 27:234–250, 2008. © 2008 Wiley‐Liss, Inc.  相似文献   

6.
The occurrence of marine turtles in the diet of white sharks, Carcharodon carcharias, is reviewed worldwide. Four records of chelonians eaten by white sharks in the Mediterranean Sea are described, which on the basis of carapace remnants confirmed both the loggerhead Caretta caretta and green turtle Chelonia mydas to be preyed upon in those waters. The condition of these remains indicates that large white sharks can ingest turtles essentially intact. As well as falling prey to white sharks, we suspect that some interactions involve turtles being grab-released in a non-predatory mannner and their survivability from such low-intensity bites or other mouthings may be quite high. The white shark may be the chief marine predator of adult chelonians in the Mediterranean Sea, albeit the impact of this predation upon turtle populations is nominal compared to other sources of mortality. Further, we give an account describing an adult ocean sunfish, Mola mola, in the stomach of a white shark taken in Italian waters.  相似文献   

7.
This paper presents a study on bioinspired closed-loop Central Pattern Generator(CPG)based control of a robot fish for obstacle avoidance and direction tracking.The biomimetic robot fish is made of a rigid head with a pair of pectoral fins,a wire-driven active body covered with soft skin,and a compliant tail.The CPG model consists of four input parameters:the flapping amplitude,the flapping angular velocity,the flapping offset,and the time ratio between the beat phase and the restore phase in flapping.The robot fish is equipped with three infrared sensors mounted on the left,front and right of the robot fish,as well as an inertial measurement unit,from which the surrounding obstacles and moving direction can be sensed.Based on these sensor signals,the closed-loop CPG-based control can drive the robot fish to avoid obstacles and to track designated directions.Four sets of experiments are presented,including avoiding a static obstacle,avoiding a moving obstacle,tracking a designated direction and tracking a designated direction with an obstacle in the path.The experiment results indicated that the presented control strategy worked well and the robot fish can accomplish the obstacle avoidance and direction tracking effectively.  相似文献   

8.
Gauldie RW 《Tissue & cell》1992,24(2):263-266
The mineralized dermal denticles of fibrillar structure of the dermal plate of the modified scales of Mola mola and Mola ramsayi have both highly specialized and archaic features suggesting that the Molidae branched from the teleost line at an early stage in its evolution.  相似文献   

9.

Background

Determining the foraging movements of pelagic seabirds is fundamental for their conservation. However, the vulnerability and elusive lifestyles of these animals have made them notoriously difficult to study. Recent developments in satellite telemetry have enabled tracking of smaller seabirds during foraging excursions.

Methodology/Principal Findings

Here, we report the first successful precision tracking of a c. 700 g seabird, the vulnerable Black Petrel, Procellaria parkinsoni, foraging at sea during the breeding season, using miniature GPS-logging technology. Employing a combination of high-resolution fixes and low-power duty-cycles, we present data from nine individual foraging excursions tracked during the chick-rearing period in February 2006.

Conclusions/Significance

We provide a snapshot of the species'' foraging range and behaviour in relation to detailed underlying bathymetry off the coast of New Zealand, finding a significant relationship between foraging movements and regions of the shelf-break. We also highlight the potential of more sophisticated analyses to identify behavioural phenomena from position data alone.  相似文献   

10.
Behaviour of a sharptail mola in the Gulf of Mexico   总被引:1,自引:0,他引:1  
A sharptail mola Masturus lanceolatus was tagged and released with a pop-up satellite archival tag in the Gulf of Mexico and tracked for 61 days. The fish travelled a horizontal distance of 594 km while generally staying in water <200 m depth and >20° C. Occasionally the sharptail mola dived to depths >700 m and experienced water colder than 6° C.  相似文献   

11.
Long-term cytogenetic monitoring was carried out in adolescents of the town of Kemerovo. In total, aberrant metaphase frequency increased from 1.53% in 1992 to 4.40% in 1996 in Kemerovo adolescents, being significantly higher than a control frequency from 1993 to 1996. In all samples, chromosome aberrations mostly included acentric fragments, while exchanges were rare. The highest number of aberrations per aberrant metaphase was 2 in Kemerovo adolescents and 1 in the control sample. The observed increase in total number of chromosome aberrations suggests that the mutagenic effect of chemical environmental pollutants on Kemerovo adolescents increased over the five years.  相似文献   

12.
Hypothalamic serotonin inhibits food intake and stimulates energy expenditure. High-fat feeding is obesogenic, but the role of polyunsaturated fats is not well understood. This study examined the influence of different high-PUFA diets on serotonin-induced hypophagia, hypothalamic serotonin turnover, and hypothalamic protein levels of serotonin transporter (ST), and SR-1B and SR-2C receptors. Male Wistar rats received for 9 weeks from weaning a diet high in either soy oil or fish oil or low fat (control diet). Throughout 9 weeks, daily intake of fat diets decreased such that energy intake was similar to that of the control diet. However, the fish group developed heavier retroperitoneal and epididymal fat depots. After 12 h of either 200 or 300 μg intracerebroventricular serotonin, food intake was significantly inhibited in control group (21–25%) and soy group (37–39%) but not in the fish group. Serotonin turnover was significantly lower in the fish group than in both the control group (−13%) and the soy group (−18%). SR-2C levels of fish group were lower than those of control group (50%, P = 0.02) and soy group (37%, P = 0.09). ST levels tended to decrease in the fish group in comparison to the control group (16%, P = 0.339) and the soy group (21%, P = 0.161). Thus, unlike the soy-oil diet, the fish-oil diet decreased hypothalamic serotonin turnover and SR-2C levels and abolished serotonin-induced hypophagia. Fish-diet rats were potentially hypophagic, suggesting that, at least up to this point in its course, the serotonergic impairment was either compensated by other factors or not of a sufficient extent to affect feeding. That fat pad weight increased in the absence of hyperphagia indicates that energy expenditure was affected by the serotonergic hypofunction.  相似文献   

13.
Foragers must often travel from a central place to exploit aggregations of prey. These patches can be identified behaviorally when a forager shifts from travel to area restricted search, identified by a decrease in speed and an increase in sinuosity of movement. Faster, more directed movement is associated with travel. Differentiating foraging behavior at patches from travel to patches is important for a variety of research questions and has now been made easier by the advent of small, GPS devices that can track forager movement with high resolution. In the summer and fall of 2012, movement data were collected from GPS devices placed on foraging trips originating in the artisanal fishing village of Desa Ikan (pseudonym), on the east coast of the Caribbean island nation of the Commonwealth Dominica. Moored FADs are human-made structures anchored to the ocean floor with fish attraction material on or near the surface designed to effectively create a resource patch. The ultimate goal of the research is to understand how property rights are emerging after the introduction of fish aggregating device (FAD) technology at the site in 1999. This paper reports on research to identify area-restricted search foraging behavior at FAD patches. For 22 foraging trips simultaneous behavioral observations were made to ground-truth the GPS movement data. Using a cumulative sum method, area restricted search was identified as negative deviations from the mean travel speed and the method was able to correctly identify FAD patches in every case.  相似文献   

14.
Surface waters from paired agricultural watersheds under controlled tile drainage (CTD) and uncontrolled tile drainage (UCTD) were monitored over 7 years in order to determine if there was an effect of CTD (imposed during the growing season) on occurrences and loadings of bacterial and viral pathogens, coliphages, and microbial source tracking markers. There were significantly lower occurrences of human, ruminant, and livestock (ruminant plus pig) Bacteroidales markers in the CTD watershed in relation to the UCTD watershed. As for pathogens, there were significantly lower occurrences of Salmonella spp. and Arcobacter spp. in the CTD watershed. There were no instances where there were significantly higher quantitative loadings of any microbial target in the CTD watershed, except for F-specific DNA (F-DNA) and F-RNA coliphages, perhaps as a result of fecal inputs from a hobby farm independent of the drainage practice treatments. There was lower loading of the ruminant marker in the CTD watershed in relation to the UCTD system, and results were significant at the level P = 0.06. The odds of Salmonella spp. occurring increased when a ruminant marker was present relative to when the ruminant marker was absent, yet for Arcobacter spp., the odds of this pathogen occurring significantly decreased when a ruminant marker was present relative to when the ruminant marker was absent (but increased when a wildlife marker was present relative to when the wildlife marker was absent). Interestingly, the odds of norovirus GII (associated with human and swine) occurring in water increased significantly when a ruminant marker was present relative to when a ruminant marker was absent. Overall, this study suggests that fecal pollution from tile-drained fields to stream could be reduced by CTD utilization.  相似文献   

15.
A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964–1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983–1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m−2), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.  相似文献   

16.
17.
According to the generally accepted view, sodium accumulation in the human body takes place in the extracellular space and is accompanied by an increase in the rate of fluid retention and body weight gain. However, this view was revised in recent studies, which demonstrated that sodium could be accumulated in the human body without expansion of the extracellular space. Sodium exchange and its effect on body weight (BW) were investigated in long-term balance studies. Three apparently healthy volunteer subjects were confined for 135 days to a ground-based model of the main unit of the Mir space station, where they were exposed to model conditions similar to conditions of actual long-term spaceflight. The daily balance of sodium and its contribution to BW changes were studied. During the period of observation, the subjects accumulated 2.973–7.324 mmol of sodium and gained 5.1–9.3 kg. Initially, there was a positive correlation between changes in the total body sodium and the BW, which reflected sodium-dependent extracellular space expansion. However, by the end of the period of isolation, the relative rate of body weight gain was lower than the relative rate of gain in the total body sodium, which suggested that sodium accumulated in an osmotically inactive form. The fact that sodium accumulated without BW gain suggests that isolation of healthy subjects in a hermetically sealed enclosure stimulates sodium accumulation in the body in an osmotically inactive form. The sodium-storing processes activated under these conditions might be localized in bone, connective tissue (skin), or cartilage. Rhythmic variation in the net sodium balance was observed and attributed to oscillations of renal excretion of aldosterone. It is obvious that the depot of osmotically inactive sodium should be taken into account in studies of cardiovascular system function and in pathophysiological approaches to edematous syndrome and hypertension.  相似文献   

18.
Kiseleva  N. V. 《Biology Bulletin》2021,48(10):1839-1842
Biology Bulletin - Abstract—In the birch–pine forests of Ilmeny Reserve the bank vole is predominant in numbers, with the pygmy wood mouse being in second place. The results of our...  相似文献   

19.
Channel Catfish Virus: a New Herpesvirus of Ictalurid Fish   总被引:4,自引:3,他引:4       下载免费PDF全文
Channel catfish virus was studied in ictalurid fish cell culture, the only system of fish, amphibian, avian, and mammalian cells found to be susceptible. Channel catfish virus infection resulted in intranuclear inclusions and extensive syncytium formation. Replication occurred from 10 to 33 C, but not higher. Best growth was from 25 to 33 C, and the amount of virus released nearly equalled the amount which remained cell-associated. The virus was labile to lipid solvents, and indirect determinations with labeled precursors and a metabolic inhibitor showed evidence of deoxyribonucleic acid. Electron microscopy showed progeny virus, about 100 nm in diameter, in various stages of development in cell nuclei by 4 hr. Present also were nuclear masses of exceptionally electron-dense lamellar material, with a unit dimension of 10 to 15 nm. Virus was enveloped at the nuclear membrane and in cytoplasmic vacuoles, resulting in virions having a diameter of 175 to 200 nm. Negative staining demonstrated icosehedral symmetry and 162 capsomeres. Our data indicate that channel catfish virus is a herpesvirus.  相似文献   

20.
Our knowledge of neural plasticity suggests that neural networks show adaptation to environmental and intrinsic change. In particular, studies investigating the neuroplastic changes associated with learning and practicing motor tasks have shown that practicing such tasks results in an increase in neural activation in several specific brain regions. However, studies comparing experts and non-experts suggest that experts employ less neuronal activation than non-experts when performing a familiar motor task. Here, we aimed to determine the long-term changes in neural networks associated with learning a new dance in professional ballet dancers over 34 weeks. Subjects visualized dance movements to music while undergoing fMRI scanning at four time points over 34-weeks. Results demonstrated that initial learning and performance at seven weeks led to increases in activation in cortical regions during visualization compared to the first week. However, at 34 weeks, the cortical networks showed reduced activation compared to week seven. Specifically, motor learning and performance over the 34 weeks showed the typical inverted-U-shaped function of learning. Further, our result demonstrate that learning of a motor sequence of dance movements to music in the real world can be visualized by expert dancers using fMRI and capture highly significant modeled fits of the brain network variance of BOLD signals from early learning to expert level performance.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号