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1.
In this study, we measured aerial visual acuity in harbor seals. As a first approach to the hypothesis that harbor seals can obtain acute aerial visual acuity mediated by the interaction of the vertical slit-shaped pupil and the corneal flattening although refractive measurements had revealed aerial myopia, visual acuity was tested as a function of luminance and pupil dilation. We analyzed aerial visual acuity (minimal resolvable stripe width) in three harbor seals in a two-alternative-forced-choice discrimination experiment. Our results further support the hypothesis that harbor seals possess an aerial visual acuity comparable to the acuity in clear waters if the vertical slit pupil does not exceed the zone of corneal flattening in bright light. When the pupil dilates with decreasing luminance, visual acuity decreases which might be due to deflected light from the stronger curved peripheral cornea.  相似文献   

2.
Recent studies have shown that harbor seals (Phoca vitulina) have an increased skeletal muscle mitochondrial volume density that may be an adaptation for maintaining aerobic metabolism during diving. However, these studies were based on single samples taken from locomotory muscles. In this study, we took multiple samples from a transverse section of the epaxial (primary locomotory) muscles and single samples from the m. pectoralis (secondary locomotory) muscle of five wild harbor seals. Average mitochondrial volume density of the epaxial muscles was 5.6%, which was 36.6% higher than predicted for a terrestrial mammal of similar mass, and most (82.1%) of the mitochondria were interfibrillar, unlike athletic terrestrial mammals. In the epaxial muscles, the total mitochondrial volume density was significantly greater in samples collected from the deep (6.0%) compared with superficial (5.0%) regions. Volume density of mitochondria in the pectoralis muscle was similar (5.2%) to that of the epaxial muscles. Taken together, these adaptations reduce the intracellular distance between mitochondria and oxymyoglobin and increase the mitochondrial diffusion surface area. This, in combination with elevated myoglobin concentrations, potentially increases the rate of oxygen diffusion into mitochondria and prevents diffusion limitation so that aerobic metabolism can be maintained under low oxygen partial pressure that develops during diving.  相似文献   

3.
Rehabilitation of marine mammals with the intent of releasing them back into nature is carried out for several species. Rehabilitation can help supporting critically endangered species, increase public awareness, and serve scientific purposes, but rehabilitation also causes concern due to risk of introducing diseases into the wild populations and genetic changes from disruption of natural selection and host-pathogen co-evolution. In this study, we investigate another potential risk from rehabilitation that has not previously been considered, i.e., anthropogenic increase in population inbreeding level. For this purpose, we performed stochastic population viability analyses of the Wadden Sea harbor seal population using VORTEX. In the Wadden Sea, rehabilitation takes place in several rehabilitation centers, and many of the seals suffer from parasitic bronchopneumonia or are orphaned. Several studies have found a correlation between helminth infection and inbreeding level. Moreover, a relation between fitness traits such as pup survival and inbreeding has been demonstrated. On this basis, we assess the effects from rehabilitating relatively inbred seals on population size and genetic diversity. We find that releasing seals significantly affect population inbreeding level and to a lesser extent population size. The effect depends on the level of inbreeding in rehabilitated seals as well as the actual number of inbred seals released.  相似文献   

4.
Haulout behaviour of harbour seals, living at the northern limit of their distributional range on Svalbard, Norway, was investigated from June to August 2000 using a combination of low-tide counts performed during boat surveys, hourly counts through 12- or 24-h cycles at specific haulout sites, and telemetric data from 37 VHF-tagged seals. The largest aggregations of seals were found at Skarvnes, a site where numbers increased steadily through the summer, reaching a peak during the moulting period in August. At this site, season/date, time of day, tidal state and temperature all significantly influenced the number of animals ashore. At the second most frequented haulout site, at Sørøya, season/date, time of day, temperature and cloud cover significantly affected the number of seals using the site. Pups were found predominantly at Sørøya (7.8 pups±6.3 SD, N=53 counts); they were less common at Skarvnes (1.0 pups±0.2 SD, N=95 counts). Haulout patterns varied by age and sex class in accordance with the demands of lactation, mating and moult. Our limited data on mother-pup pairs suggest that they are closely associated during the nursing period, spending approximately 50% of their time hauled out together. Post lactation, most adult females left haulout areas for periods of up to several days. The haulout behaviour of adult males suggested that they adjusted their behaviour to follow female distribution and movement patterns during the breeding period. Most juveniles and adults of both sexes stayed ashore for prolonged periods during moulting, which took place first in juveniles, then in adult females and finally in adult males. The results of our study show that the basic haulout behaviour patterns of harbour seals at Svalbard are similar to this species behaviour at lower latitudes.  相似文献   

5.
Parasites were collected from 107 harbour seals (Phoca vitulina) found on the coasts of Schleswig-Holstein, Germany, between 1997 and 2000. The prevalence of the parasites and their associated pathology were investigated. Eight species of parasites, primarily nematodes, were identified from the examined organs: two anisakid nematodes (Pseudoterranova decipiens (sensu lato), Contracaecum osculatum (sensu lato)) from the stomach, Otostrongylus circumlitus (Crenosomatidae) and Parafilaroides gymnurus (Filaroididae) from the respiratory tract, one filarioid nematode (Acanthocheilonema spirocauda) from the heart, two acanthocephalans, Corynosoma strumosum and C. semerme (Polymorphidae), from the intestine and an ectoparasite, Echinophthirius horridus (Anoplura, Insecta). Lungworm infection was the most prominent parasitological finding and secondary bacterial bronchopneumonia the most pathogenic lesion correlated with the parasites. Heavy nematode burdens in the respiratory tract were highly age-related and more frequent in young seals. A positive correlation was observed between high levels of pulmonary infection and severity of bronchopneumonia. The prevalence of lungworms in this study was higher than in seals that died during the 1988/1989 Phocine Distemper Virus epidemic, and the prevalence of acanthocephalans and heartworms had decreased compared to findings from the first die-off.  相似文献   

6.
This study on harbor seal (Phoca vitulina) pups of the North Sea evaluated concentrations of 14 essential and non-essential elements (Al, As, Be, Ca, Cd, Cr, Fe, Mn, Mo, Ni, Pb, Se, Sn, and Zn) in whole blood samples. The essential elements are analyzed to give references for health status determinations of pups. The measurement of classic toxic metals, like Pb or Cd, and other elements that may be in toxic concentrations in blood, is important due to their influence on health, particularly on the immune system. Blood samples of six seal pups found on the German Wadden Sea coast of Schleswig-Holstein in 2004 and transported to the Seal Centre Friedrichskoog, Germany were collected. The blood sampling was performed three times, immediately after collection of the newborns, after 1.5 months, and after 2 months before their release back into the wild. Inductively coupled plasma mass spectrometry and total reflection X-ray fluorescence spectrometry were used to determine the element concentrations. We found higher concentrations of Al, As, Fe, Mo, and Zn in blood samples of newborns compared to samples collected later, probably due to transplacental and lactational transfer from mother to fetus. Furthermore, there is a high need for, in particular, Fe and Zn in the developing organism, which may cause reduced values after some month. In contrast, the concentrations of Be, Cd, Ca, Cr, Pb, Mn, Ni, Se, and Sn, which were low in newborns and increased during the study, may be due to the fish fed to infant pups. Compared to free-ranging adults, in pups, the concentrations of Al, Ni, and Pb were higher in contrast to lower concentrations of As, Mn, and Mo. This case study is the first report on element levels in harbor seal pups of the North Sea.  相似文献   

7.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.  相似文献   

8.
New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora: Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii , Rumex densiflorus var. pycnanthus , R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage.  相似文献   

9.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.  相似文献   

10.
As the putative sister group to the arthropods, onychophorans can provide insight into ancestral developmental mechanisms in the panarthropod clade. Here, we examine the expression during segmentation of orthologues of wingless (Wnt1) and engrailed, two genes that play a key role in defining segment boundaries in Drosophila and that appear to play a role in segmentation in many other arthropods. Both are expressed in segmentally reiterated stripes in all forming segments except the first (brain) segment, which only shows an engrailed stripe. Engrailed is expressed before segments are morphologically visible and is expressed in both mesoderm and ectoderm. Segmental wingless expression is not detectable until after mesodermal somites are clearly distinct. Early engrailed expression lies in and extends to both sides of the furrow that first demarcates segments in the ectoderm, but is largely restricted to the posterior part of somites. Wingless expression lies immediately anterior to engrailed expression, as it does in many arthropods, but there is no precise cellular boundary between the two expression domains analogous to the overt parasegment boundary seen in Drosophila. Engrailed stripes extend along the posterior part of each limb bud, including the antenna, while wingless is restricted to the distal tip of the limbs and the neurectoderm basal to the limbs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

11.
The aim of this study was to determine if individual ticks among the progeny of a single female Rhipicephalus (Boophilus) microplus tick removed from cattle under natural conditions are the result of mating with one or several males. To this end, simulations were run using an existing dataset of genotypes from 8 microsatellite loci to predict the number of samples required and the best locus. Subsequently, 14–22 progeny from each of 15 engorged female ticks removed from three cows, and the engorged females themselves, were genotyped for the BmM1 locus and the minimum number of potential male parents was determined for each progeny group. Of the 15 progeny groups, 10 must have been sired by more than one male, as indicated by the presence of five unique alleles among the progeny or three unique alleles that could not have been contributed by the female. This finding demonstrates multiple paternity in R. microplus.  相似文献   

12.
We investigated the effects of temperature, photoperiod, food and host availability, and body size on the overwintering abilities of the egg parasitoid Anaphes nitens Girault (Hymenoptera, Mymaridae) under natural conditions. Seven groups of eighty females received one of four treatments (n = 20): (i) honey and hosts, (ii) water and hosts, (iii) honey, or (iv) water. Seven groups of forty males received only honey or water (n = 20). To test if short day-length is the main cue for larval dormancy, the experiment was replicated inside a climate chamber at 20°C and under a winter photoperiod. A. nitens overwinters because of quiescence or oligopause inside the hosts and increased adult longevity. Mean pre-emergence mortality was up to 26% indoors and 15.2% outdoors, males being more affected. Development time had a significant and positive effect on body size. Honey-fed females without hosts had the highest longevity (53 days). Mother’s diet and size affected development time, body size, longevity, and fecundity of the progeny. The results confirm the good adaptation of the parasitoid to the environmental conditions of NW Spain and its ability to synchronize its life cycle with the phenology of the host. Handling editor: Drik Babendreier.  相似文献   

13.
Single (unpaired) vegetative cells of freshwater pennate diatom Neidium cf. ampliatum differentiated into gametangia and produced a single zygote (auxospore) via a pedogamic process. The gametic nuclei fused after auxospore expansion had begun. The auxospore expanded in parallel to the apical axis of the gametangium.  相似文献   

14.

Background

Gonadotropin releasing hormone (GnRH) is responsible for stimulation of gonadotropic hormone (GtH) in the hypothalamus-pituitary-gonadal axis (HPG). The regulatory mechanisms responsible for brain specificity make the promoter attractive for in silico analysis and reporter gene studies in zebrafish (Danio rerio).

Results

We have characterized a zebrafish [Trp7, Leu8] or salmon (s) GnRH variant, gnrh 3. The gene includes a 1.6 Kb upstream regulatory region and displays the conserved structure of 4 exons and 3 introns, as seen in other species. An in silico defined enhancer at -976 in the zebrafish promoter, containing adjacent binding sites for Oct-1, CREB and Sp1, was predicted in 2 mammalian and 5 teleost GnRH promoters. Reporter gene studies confirmed the importance of this enhancer for cell specific expression in zebrafish. Interestingly the promoter of human GnRH-I, known as mammalian GnRH (mGnRH), was shown capable of driving cell specific reporter gene expression in transgenic zebrafish.

Conclusions

The characterized zebrafish Gnrh3 decapeptide exhibits complete homology to the Atlantic salmon (Salmo salar) GnRH-III variant. In silico analysis of mammalian and teleost GnRH promoters revealed a conserved enhancer possessing binding sites for Oct-1, CREB and Sp1. Transgenic and transient reporter gene expression in zebrafish larvae, confirmed the importance of the in silico defined zebrafish enhancer at -976. The capability of the human GnRH-I promoter of directing cell specific reporter gene expression in zebrafish supports orthology between GnRH-I and GnRH-III.
  相似文献   

15.
Two protocols were developed for the efficient regeneration of Sinningia speciosa from leaf explants via two developmental pathways. The first method involved formation of callus and buds, followed by subsequent root growth, in Murashige and Skoog medium (MS) containing 2.0 mg l−1 6-benzylaminopurine (BA) and 0.2 mg l−1 α-naphthalene acetic acid (NAA), with a regeneration efficiency of 99.0%. The second method involved producing callus and roots, followed by subsequent formation of buds, in MS medium supplemented with 1.0–5.0 mg l−1 NAA, and resulted in a regeneration efficiency of 90.4%. Our experiments indicate that the root-first pathway resulted in a lower plant regeneration efficiency. Through five continual generations using the buds-first method, a total of 215 regenerated plants were obtained in the last generation, and eight exhibited a phenotype we named tricussate whorled phyllotaxis (twp). Six of the regenerated twp variant plants maintained their tricussate whorled phyllotaxis phenotype, showing no other abnormalities, while one reverted to a wild type before flowering and another formed two rounds of sepals. Physiological analysis revealed that the twp plants responded differently than wild type to exogenous NAA and 2,3,5-triiodobenzoic acid (TIBA), while high-performance liquid chromatography (HPLC) analysis showed that the levels of endogenous indole-3-acetic acid (IAA) and gibberellin (GA) were lower in twp than wild-type plants. These results suggest that the formation of the twp mutant may be related to phytohormones and that the twp variant could be an important material for investigating the molecular mechanism of plant phyllotaxis patterning.  相似文献   

16.
A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.  相似文献   

17.
Studying Pneumocystis has proven to be a challenge from the perspective of propagating a significant amount of the pathogen in a facile manner. The study of several fungal pathogens has been aided by the use of invertebrate model hosts. Our efforts to infect the invertebrate larvae Galleria mellonella with Pneumocystis proved futile since P. murina neither caused disease nor was able to proliferate within G. mellonella. It did, however, show that the pathogen could be rapidly cleared from the host.  相似文献   

18.
A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.  相似文献   

19.
Tropilaelaps mercedesae is a serious ectoparasite of Apis mellifera in China. The aim of this study was to investigate the infestation rates and intensity of T. mercedesae in A. mellifera in China, and to explore the relative importance of climate, district, management practices and beekeeper characteristics that are assumed to be associated with the intensity of T. mercedesae. Of the 410 participating apiaries, 379 apiaries were included in analyses of seasonal infestation rates and 352 apiaries were included in multivariable regression analysis. The highest infestation rate (86.3%) of T. mercedesae was encountered in autumn, followed by summer (66.5%), spring (17.2%) and winter (14.8%). In autumn, 28.9% (93) of the infested apiaries were in the north (including the northeast and northwest of China), 71.1% (229) were in the central and south (including east, southeast and southwest China), and 306 apiaries (82.9%) were co-infested by both T. mercedesae and Varroa. Multivariable regression analysis showed that geographical location, season, royal jelly collection and Varroa infestation were the factors that influence the intensity of T. mercedesae. The influence of beekeeper’s education, time of beekeeping, operation size, and hive migration on the intensity of T. mercedesa was not statistically significant. This study provided information about the establishment of the linkage of the environment and the parasite and could lead to better timing and methods of control.  相似文献   

20.
Previously, we described the unique feature of telomeric regions in Iberian shrew Sorex granarius: its telomeres have two ranges of size, very small (3.8 kb of telomeric repeats on average) and very large discontinuous telomeres (213 kb) interrupted with 18S rDNA. In this study, we have demonstrated extraordinary replication pattern of S. granarius large telomeres that have not been shown before in other studied mammal. Using the ReD-FISH procedure, we observed prolonged, through S period, large telomere replication. Furthermore, revealed ReD-FISH asymmetric signals were probably caused by partial replication of telomeres within an hour of 5-bromodeoxyuridine treatment due to the large size and special organization. We also found that in contrast to the telomeric halo from primary fibroblasts of bovine, mink, and common shrew, telomere halo of S. granarius consists of multiple loops bundled together, some of which contain rDNA. Here, we suggested several replicons firing possibly stochastic in each large telomere. Finally, we performed the TIF assay to reveal DNA damage responses at the telomeres, and along with TIF in nuclei, we found large bodies of telomeric DNA and ?-H2AX in the cytoplasm and on the surface of fibroblasts. We discuss the possibility of additional origin activation together with recombination-dependent replication pathways, mainly homologous recombination including BIR for replication fork stagnation overcoming and further S. granarius large telomere replication.  相似文献   

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