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1.
Between November and February in the years 1993/1994 to 1999/2000, 153 southern elephant seals, Mirounga leonina, were stomach lavaged at King George Island. Fish occurred in 16 of 108 stomachs containing food items. Myctophids were the dominant fish prey, contributing 76.6% of the 145 sagittal otoliths found. The most important prey species was Gymnoscopelus nicholsi, which constituted 69% of the otoliths and occurred in 75% of stomach samples. Next in importance was the nototheniid Pleuragramma antarcticum, which occurred in 31.3% of samples and represented 11.7% in numbers. We suggest that while myctophids may be the dominant fish prey of elephant seals in areas close to King George Island, they are probably replaced by P. antarcticum as seals migrate towards higher latitudes where this fish is extremely abundant.  相似文献   

2.
The foraging distribution of marine predator populations is important for effective modelling and management of pelagic marine systems. We tracked 31 juvenile southern elephant seals from Macquarie Island (158°57E, 54°30S) over their annual post-moult and mid-year trips to sea. We calculated the amount of time spent in regional fisheries management areas and within bounded oceanographic regions. During the austral summer, juvenile seals spent over 90% of their time south of the Antarctic Polar Front and ~80% within fisheries management regions [Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and exclusive economic zones]. In winter, seals spent ~75% of their time in the region bounded by the Antarctic Polar Front and the southern boundary of the Antarctic Circumpolar Current, and ~60% within fisheries management regions. The time spent per region differed significantly between summer and winter. Our results demonstrate that juvenile southern elephant seals from Macquarie Island spent more time south of the Antarctic Polar Front and within fisheries management areas than previously suspected.  相似文献   

3.
Within the Southern Ocean, Patagonian toothfish (Dissostichus eleginoides Smitt) and southern elephant seals (Mirounga leonina Linnaeus) forage mainly on fish and cephalopods. From what is known of their diets, the proportion of fish is greatest in toothfish diet. When foraging at-sea for squid, elephant seals and toothfish most often co-occur over continental shelves and submarine plateaux surrounding sub-Antarctic land masses within the Southern Ocean. I used traditional (non-molecular) techniques to compare the squid diet of these two predators. Of the 21 squid species identified, 10 were common to the diets of both predators. One species, Gonatus antarcticus, dominated (61%) the biomass of squid consumed by toothfish, but was of little importance to the elephant seals (2.3%). By contrast, Martialia hyadesi was the most important single species to the elephant seals diet (29%), but it contributed 1% to the toothfish diet. Onychoteuthids (Kondakovia longimana, Moroteuthis ingens and Morotenthis knipovitchi) were important to both predators diets. The median sizes of five cephalopod species (Slosarczykovia circumantarctica, Galiteuthis glacialis, Gonatus antarcticus, Moroteuthis ingens and Moroteuthis knipovitchi) which were common to both the seal and toothfish diets, were significantly larger in the toothfish stomachs than in the elephant-seal stomachs. Percent similarity indices for the squids that overlapped both diets were in some cases as high as 100%. However, after between-species differences in prey size consumption were accounted for, the similarities fell to between 20 and 50%. These results indicate that the strength of the trophic interaction between the seals and the fish might be weaker than previously thought. The consumption of significantly different-sized squid can also be used to suggest spatial (vertical) foraging separation of these two predators because there is evidence for ontogenetic change in the size of squid species with depth; older, and thus larger, squids live deeper than smaller individuals of the same species.  相似文献   

4.
5.
Seventy-seven immobilizations were carried out on adult male southern elephant seals at Stranger Point, Isla 25 de Mayo (King George Island) using a combination of Zoletil® (tiletamine and zolazepam) and ketamine in order to obtain biological samples. During 2006/2007, 22 males were immobilized at the beginning of their breeding period (EB), 19 of which were recaptured at the end of breeding (LB). Four were given only once at an unknown stage of breeding (USB) and 18 males were immobilized at the beginning of molting (BM). During 2007/2008, 14 adult males were immobilized at an USB. Zoletil® was administered using an automatic discharge device, whereas ketamine was injected directly with a syringe, and was used only when the initial sedation was not enough to carry out the programmed sampling. The initial mean dose of Zoletil® was 1,387 ± 304 mg, which represented 0.60 ± 0.14 mg/kg, range 0.36–1.05, n = 77. In 47 procedures, an average dose of 1.04 ± 0.66 mg/kg of ketamine was added. Mean immobilization time was 34 ± 14 min. In 25 out of the 77 procedures, males showed apnea, which lasted 8 ± 4 min (range 2–15 min). The necessary doses of Zoletil® and ketamine to attain immobilization differed between stages. For animals taken twice, doses (mg/kg) of Zoletil® and ketamine were significantly higher at the beginning than at the end of breeding. During molting, the doses of Zoletil® given were significantly lower than those used during breeding, although the proportion of animals that required ketamine during molting was significantly higher than during breeding. Zoletil® proved to be a safe immobilizing agent for field work on adult males of this species, given the wide range of doses used without any serious consequences. Furthermore, the addition of ketamine was useful when the initial sedation was not satisfactory or for prolonging the immobilization period in a practical and reliable way.  相似文献   

6.
Total numbers of adult female southern elephant seals (cows) breeding at Macquarie Island were determined for 19 of the 52 year period between 1952 and 2004. Totals for 1952–1987 (exc. 1959 and 1985) were estimated from the relationship between censuses of the isthmus study area and concurrent censuses for the whole island. Totals for 1987–2004 were obtained by direct census of the entire island in mid-October. Cow numbers decreased from a maximum of about 40,000 in the 1950s to a minimum of 18,300 in 2000, but then increased slightly to 19,200 in 2004. Nonlinear and post-hoc linear analysis of the count data identified 1999 as the year when the exponential rate of change (r) slowed from −1.4% per annum to near zero. The rate of change was not uniform for each census sub-area counted (1987–2004), suggesting that certain terrestrially based density-dependent mechanisms were influencing the annual distribution of cows.  相似文献   

7.
Extractive foraging in nonhuman primates may involve different levels of technical complexity in terms of the number of actions that must be performed and the manual dexterity involved. We describe the extractive foraging of caterpillars in wild northern pig-tailed macaques (Macaca leonina) at Khao Yai National Park, Thailand. The study group, observed from May to December 2016 (n = 146 days), comprised 60–70 habituated individuals, including 3–4 adult males, 20–23 adult females, and 36–47 immatures. Four adult males and five adult females, observed from September to November 2016 for a total of 24 days, were selected for focal animal sampling. Northern pig-tailed macaques were observed eating at least two families (Erebidae and Limacodidae) and three genera (Macrobrochis sp., Phlossa sp. and Scopelodes sp.) of caterpillars. While the monkeys ate short and small caterpillars with stinging setae and non-setae caterpillars without processing, they performed extensive caterpillar-rubbing behavior on large and long caterpillars with stinging setae. Based on 61 extractive foraging bouts, we found that caterpillar rubbing was hierarchically organized into five stages and 12 elements. Five stages of behavior sequence started with picking the caterpillar up, transporting it to a substrate, rubbing it to remove stinging setae, ingesting it, and then cleaning hands and mouth. Only adult macaques were observed using a leaf to rub stinging caterpillars.  相似文献   

8.
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.
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   

11.
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   

12.
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   

13.
14.
Traditionally viewed as an Andean grain crop,Chenopodium quinoa Willd. includes domesticated populations that are not Andean, and Andean populations that are not domesticated. Comparative analysis of leaf morphology and allozyme frequencies have demonstrated that Andean populations, both domesticated(quinua) and free-living(ajara), represent an exceptionally homogeneous unit that is well differentiated from allied domesticates of coastal Chile(quingua) and freeliving populations of the Argentine lowlands(C. hircinum). This pattern of relationships indicates that Andean populations represent a monophyletic crop/weed system that has possibly developed through cyclic differentiation (natural vs. human selection) and introgressive hybridization. Relative levels of variation suggest that this complex originated in the southern Andes, possibly from wild types allied withC. hircinum, with subsequent dispersal north to Colombia and south to the Chilean coast. Coastal populations were apparently isolated from post-dispersal differentiation and homogenization that occurred in the Andes. Other data point toward a center of origin in the northern Andes with secondary centers of genetic diversity subsequently developing in the southern Andes and the plains of Argentina. Comparative linkage of South American taxa, all tetraploid, with North American tetraploids of the subsection will eventually clarify this problem. While the possibility of a direct phyletic connection betweenC. quinoa and the Mexican domesticate(C. berlandieri subsp. nuttalliae,) cannot be excluded, available evidence indicates that the latter represents an autonomous lineage that is associated with the basal tetraploid, C. b. subsp.berlandieri, through var.sinuatum, whereas South American taxa show possible affinities to either var. zschackei or var.berlandieri. An extinct domesticate of eastern North America,C. b. subsp.jonesianum, represents either another instance of independent domestication, possibly from subsp. b. var.zschackei, or a northeastern outlier of subsp.nuttalliae.  相似文献   

15.
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   

16.
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   

17.

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   

18.
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   

19.
Lin X  Minamisawa N  Takechi K  Zhang W  Sato H  Takio S  Tsukaya H  Takano H 《Planta》2008,228(4):601-608
ANGUSTIFOLIA (AN), a plant homolog of C-terminal binding protein, controls the polar elongation of leaf cells and the trichome-branching pattern in Arabidopsis thaliana. In the present study, degenerate PCR was used to isolate an ortholog of AN, referred to as LgAN, from larch (Larix gmelinii). The LgAN cDNA is predicted to encode a protein of 646 amino acids that shows striking sequence similarity to AN proteins from other plants. The predicted amino acid sequence has a conserved NAD-dependent 2-hydroxy acid dehydrogenase (D2-HDH) motif and a plant AN-specific LxCxE/D motif at its N-terminus, as well as a plant-specific long C-terminal region. The LgAN gene is a single-copy gene that is expressed in all larch tissues. Expression of the LgAN cDNA rescued the leaf width and trichome-branching pattern defects in the angustifolia-1 (an-1) mutant of Arabidopsis, showing that the LgAN gene has effects complementary to those of AN. These results suggest that the LgAN gene has the same function as the AN gene.  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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