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1.
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
2.
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
3.
E. Banguera-Hinestroza A. Bjørge R. J. Reid P. Jepson A. R. Hoelzel 《Conservation Genetics》2010,11(5):1823-1836
In this paper we use mitochondrial and microsatellite DNA variation to investigate the mechanisms that underlie the evolution
of population structure in a highly mobile marine mammal, the white-beaked dolphin. We found moderate genetic diversity (h) at mtDNA, but low nucleotide diversity (π) (0.7320 ± 0.0031 and 0.0056 ± 0.0004, respectively), consistent with expectations
for a recent expansion. Analyses based on mismatch distributions further suggested a demographic expansion in the Norwegian-Barents
Sea population and a spatial expansion in the British isles-North Sea population, implying distinct demographic histories.
F
ST values showed clear differentiation among these two populations, but no difference was found between putative populations
separated by the English Channel. Our data suggest a stepwise pattern of expansion, dependent on available coastal habitat.
The conservation implications are a need to protect local populations isolated by an expanse of deep water, and in particular,
a population along the British coasts and in the North Sea as separate from the North Norway-Barents Sea population. It is
also evident that overall diversity was reduced, probably during the last glacial epoch. 相似文献
4.
In a series of field experiments Diabrotica beetle herbivory was found to influence the magnitude of inbreeding depression in Cucurbita pepo ssp. texana, an annual monoecious vine. Beetles damage flowers and fruits and chew dime-sized holes in leaf tissue between major veins. Inbred plants were found to be more likely to be damaged by beetles and to have more leaves damaged per plant than outcrossed plants. A positive linear association was found between the coefficient of inbreeding and the magnitude of leaf damage, whereas a negative association was found between coefficient of inbreeding and several male and female fitness traits. When pesticides were used to control beetle herbivory, the interaction between coefficient of inbreeding and pesticide treatment was significant for fruit production and marginally significant for pollen quantity per anther. Therefore, the magnitude of inbreeding depression in C. pepo ssp . texana varies depending on the severity of beetle herbivory. 相似文献
5.
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
6.
Noel H. Holmgren 《Brittonia》2018,70(1):115-139
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
7.
James J. Finneran Hollis R. London Dorian S. Houser 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2007,193(8):835-843
Envelope following responses were measured in two bottlenose dolphins in response to sinusoidal amplitude modulated tones
with carrier frequencies from 20 to 60 kHz and modulation rates from 100 to 5,000 Hz. One subject had elevated hearing thresholds
at higher frequencies, with threshold differences between subjects varying from ±4 dB at 20 and 30 kHz to +40 dB at 50 and
60 kHz. At each carrier frequency, evoked response amplitudes and phase angles were plotted with respect to modulation frequency
to construct modulation rate transfer functions. Results showed that both subjects could follow the stimulus envelope components
up to at least 2,000 Hz, regardless of carrier frequency. There were no substantial differences in modulation rate transfer
functions for the two subjects suggesting that reductions in hearing sensitivity did not result in reduced temporal processing
ability. In contrast to earlier studies, phase data showed group delays of approximately 3.5 ms across the tested frequency
range, implying generation site(s) within the brainstem rather than the periphery at modulation rates from 100 to 1,600 Hz.
This discrepancy is believed to be the result of undersampling of the modulation rate during previous phase measurements. 相似文献
8.
Three wild red-legged partridges (Alectoris rufa) from intensively managed hunting areas in Spain were received for necropsy. They showed granulomatous lesions in different parts of the body, mainly in liver and spleen. Microscope examination of the granulomas showed central caseous necrosis and large amounts of acid-fast bacilli, surrounded by epitheloid cells, giant cells, and lymphocytes. Attempts to isolate and culture the bacillus in Colestsos medium were unsuccessful, but the polymerase chain reaction technique revealed the presence of microorganisms belonging to the Mycobacterium avium complex in one of the partridges. This is the first report of avian tuberculosis in free-living red-legged partridges. 相似文献
9.
Detection thresholds for an increment in duration of a 10-kHz pure tone were determined in the NMRI mouse using a Go/NoGo-procedure and the method of constant stimuli. Thresholds for reference durations of 50, 100 and 200 ms were obtained presenting the signals at a fixed level or at a level varying by ±3 dB. Thresholds were determined using signal-detection theory (d=1.0 or d=1.8) and the criterion of 50% correct responses. For a fixed level, the average Weber fraction T/T (criterion of d=1.8) significantly decreased from 1.18 or 1.23 at reference durations of 50 or 100 ms, respectively, to 0.97 at a reference duration of 200 ms. Thresholds were on average reduced by 46.8 or 55.4% for the threshold criteria d=1 or 50% correct responses, respectively. There was no effect of randomizing the level on the discrimination threshold. Duration discrimination in the NMRI mouse does not follow Webers law. The results are consistent with a mechanism summing up neural impulses over the duration of the stimulus. The psychoacoustic data are compared with results obtained by Brand et al. (J Acoust Soc Am 51:1291–1223, 2000) on the representation of acoustic signal duration in the mouse inferior colliculus. 相似文献
10.
Karin Nuernberg Jaroslav Slamecka Jozef Mojto Jozef Gasparik Gerd Nuernberg 《European Journal of Wildlife Research》2011,57(4):795-803
The aim of this investigation was to characterise the fatty acid composition within intramuscular fat (IMF) of two muscles
(breast and thigh) from 28 pheasants, ten wild ducks and 27 black coots from Slovakia. A high variability for all single fatty
acids (FA) and the total fat concentration in muscles of wild birds was identified. Black coots deposited the highest fat
in breast muscle whereas wild ducks and pheasants accumulated more lipids in thigh muscle. In general, the content of polyunsaturated
fatty acids (PUFA) of the IMF in wild bird muscles was high, and the saturated FA concentration was lower compared with muscles
of domestic farm animals. The ratio between PUFA and saturated fatty acids (PSQ) ranked between 0.6 and 1.2, and the ratio
of n-6/n-3 fatty acid was favourably low in black coot and wild pheasants (3.2 and 2.9, respectively). Farmed pheasants had increased
IMF and more saturated and n-6 fatty acids deposited in thigh muscle but not in breast muscle. 相似文献
11.
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
12.
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.13.
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
14.
Poulícková A 《Folia microbiologica》2008,53(2):125-129
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
15.
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
16.
A Candida rugosa lipase immobilized on polypropylene powder was employed as the biocatalyst for the enantioselective hydrolysis of (R, S)-suprofen 2,2,2-trifluorothioester in cyclohexane, in which trioctylamine was added as the catalyst to perform in situ racemization of the remaining (R)-thioester. A hollow-fiber membrane was also integrated with the dynamic kinetic resolution process in order to continuously extract the desired (S)-suprofen into an aqueous solution containing NaOH. A kinetic model for the whole process (operating in batch and feed-batch modes) was developed, in which enzymatic hydrolysis and deactivation, lipase activation, racemization and non-enantioselective hydrolysis of the substrate by trioctylamine, and reactive extraction of (R)- and (S)-suprofen into the aqueous phase in the membrane were considered. Theoretical predictions from the model for the time-course variations of substrate and product concentrations in each phase were compared with experimental data. 相似文献
17.
Geographic Information System (GIS) tools are applied to a comprehensive database of 3514 records of wild Arachis species to assist in the conservation and utilisation of the species by: (a) determining the distributional range of species and their abundance; (b) characterising species environments; (c) determining the geographical distribution of species richness; and (d) determining the extent to which species are associated with river basins. Distributional ranges, climatic variables and indices of endemism for each species are tabulated. A. duranensis Krapov. & W.C. Gregory, the most probable donor of the A genome to the cultivated peanut, is distributed in close proximity to both the proposed donor of the B genome, A. ipaënsis, and the closest wild relative of the cultigen, A. monticola Krapov. & Rigoni. This region in the eastern foothills of the Andes and the adjoining chaco regions of Argentina, Bolivia and Paraguay, is a key area for further exploration for wild Arachis. An area of particularly high species richness occurs in the State of Mato Grosso, close to the Gran Pantanal in southwest Brazil. Seventy-one percent of the species were found to have some degree of association with water catchment areas, although in most cases it was difficult to determine whether this was due to climatic adaptation reasons, restricted dispersal due to geocarpic habit, or the role of watercourses as a principal dispersal agent. In only two cases could climatic adaptation be eliminated as the reason for species distribution. 相似文献
18.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae. 相似文献
19.
Polar bears, Ursus maritimus, throughout their range, are nutritionally dependent on ringed (Phoca hispida) and bearded seals (Erignathus barbatus), which are predominantly caught on the sea ice. Other marine prey species are caught and consumed, but less frequently.
As the annual sea ice retreats, polar bears throughout their range are forced ashore, where they mostly live off their stored
adipose tissue. However, while land-bound they have been observed catching birds and terrestrial mammals. Although polar bears
evolved from brown bears (U. arctos), direct observations of polar bears diving for and catching fish have not been reported. Here, we document observations
of a young male polar bear catching Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus
quadricornis) by diving in Creswell Bay, Nunavut. We recorded six search bouts, where six fish were caught during dives, which were preceded
by a snorkel. The average dive and snorkel length was (mean ± SD) 13 ± 5 and 6 ± 2 s, respectively. 相似文献
20.
Sarawood Sungkaew Atchara Teerawatananon John A. N. Parnell Chris M. A. Stapleton Trevor R. Hodkinson 《Kew Bulletin》2008,63(4):669-673
Summary A new monotypic bamboo genus Phuphanochloa (Poaceae: Bambusoideae) from north-eastern Thailand is described, together with a new species, P. speciosa. 相似文献