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1.
The European bitterling, Rhodeus amarus, is a non-indigenous fish species in British fresh waters. It lays its eggs in unionid mussels which themselves are vulnerable
to fouling by the non-indigenous zebra mussel, Dreissena polymorpha. Observations from an unmanipulated natural system showed that only 27% of zebra mussel-fouled Unio pictorum hosted bitterling, while 47% of unfouled U. pictorum hosted bitterling. We conducted a field experiment in the River Great Ouse catchment, Cambridgeshire, England in May–June
2007 and 2008 to quantify the impact of zebra mussels on bitterling load in host mussels. Zebra mussel-fouled unionids were
significantly less likely to host bitterling than unfouled unionids. The number of unionids hosting bitterling did not differ
significantly whether the zebra mussels fouling the unionid were alive or dead. Bitterling appeared to discriminate against
zebra mussel-fouled unionids less as the 2007 breeding season advanced, potentially because preferred unfouled unionids had
a higher bitterling load, and were therefore relatively lower quality hosts than at the start of the breeding season. 相似文献
2.
Vera Pavlova 《Biological invasions》2012,14(3):509-514
The deepwater profunda morph of quagga mussel Dreissena bugensis was found for the first time in the European part of its range. The mussels of this morph were found in the Cheboksary Reservoir
situated in the midstream of the Volga River (Russian Federation). Traditional and geometric morphometrics confirm the similarity
of studied specimens to profunda mussel described from the Great Lakes of North America. In the Cheboksary Reservoir the deepwater mussels live at depth of
26.5 m on sandy-pebbled substrate at conditions of high water velocity (>0.5 m/s), i. e. in the conditions unusual for American
profunda. This fact reflects evident ecological plasticity of this morph. Discovery of the deepwater morph of quagga mussel in the
European part of its range indicates that possibility of realization of the deepwater phenotype is inherent to this species.
It is suggested that quagga mussel may possess two alternative developmental pathways that could be realized in appropriate
conditions. Presumably, certain depth and/or water pressure may serve as signaling factors for activating the “deepwater”
developmental pathway. The presence of deepwater and shallow-water morphs is very important adaptive feature for sedentary
organisms such as dreissenids that are unable to select habitat actively since this feature allows for successful colonization
of both deep and shallow water habitats. 相似文献
3.
I. S. Voroshilova V. S. Artamonova A. A. Makhrov Yu. V. Slyn’ko 《Biology Bulletin》2010,37(5):542-547
Dreissenids display a high diversity of shell morphology, and it is frequently difficult to ascribe some individuals from
mixed populations to one of the two species, Dreissena polymorpha (Pallas, 1771) or D. bugensis (Andrusov, 1897). Presumably, such individuals may be interspecific hybrids. We have analyzed species-specific allozyme loci
of the typical representatives of these two mussel species and putative interspecific hybrids. A natural interspecific hybrid
between D. polymorpha and D. bugensis was discovered for the first time by genetic methods. It has been demonstrated that D. bugensis was a maternal parent. 相似文献
4.
Molly Van Appledorn David A. Lamb Kinneret Albalak Catherine E. Bach 《Hydrobiologia》2007,575(1):441-445
Invasive species can drive native organisms to extinction by limiting movement and accessibility to essential resources. The
purpose of this study was to determine if zebra mussels (Dreissena polymorpha) affect the burrowing ability and growth rate of a native snail, Campeloma decisum. Snails with and without zebra mussels were collected from Douglas Lake, MI, and burrowing depths were studied in both the
laboratory and Douglas Lake. Growth rates were calculated as the amount of shell growth from 2004 to 2005. Both the tendency
of snails to burrow and the depth to which they burrowed into the substrate were significantly decreased by the presence of
zebra mussels on snail shells in both laboratory and lake experiments. There was no difference in the percentage of snails
that exhibited growth as a function of zebra mussel presence. However, for those snails that grew, there was a 50% higher
growth rate for snails without zebra mussels compared to snails with zebra mussels. These negative effects of zebra mussels
on growth and burrowing ability will likely lead to decreases in snail population densities in the future.
Handling editor: S. Wellekens 相似文献
5.
Habitat engineering role of the invasive zebra mussel Dreissena polymorpha (Pallas) was studied in the Curonian lagoon, a shallow water body in the SE Baltic. Impacts of live zebra mussel clumps and
its shell deposits on benthic biodiversity were differentiated and referred to unmodified (bare) sediments. Zebra mussel bed
was distinguished from other habitat types by higher benthic invertebrate biomass, abundance, and species richness. The impact
of live mussels on biodiversity was more pronounced than the effect of shell deposits. The structure of macrofaunal community
in the habitats with >103 g/m2 of shell deposits devoid of live mussels was similar to that found within the zebra mussel bed. There was a continuous shift
in species composition and abundance along the gradient ‘bare sediments—shell deposits—zebra mussel bed’. The engineering
impact of zebra mussel on the benthic community became apparent both in individual patches and landscape-level analyses. 相似文献
6.
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
7.
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
8.
Daniel Cataldo Alicia Vinocur Inés O′Farrell Esteban Paolucci Valentín Leites Demetrio Boltovskoy 《Hydrobiologia》2012,680(1):25-38
In order to assess the effects of the introduced bivalve Limnoperna fortunei on water-column properties of Salto Grande reservoir, experiments were conducted using six 400 L mesocosms: 2 with 100 mussels,
2 with 300 mussels, and 2 controls (without mussels). At 0, 1, 2, 3, 7, 14, 21, 28, and 35 days we measured nutrient and chlorophyll
a concentrations, counted and identified the phytoplankton, and estimated the density, size, and number of cells of the colonies
of Microcystis spp. Cumulative periphyton growth and total accumulated sediments were assessed in all enclosures at the end of the experiment.
Throughout the experiment, in the controls ammonia and phosphates dropped to near zero, whereas in the mesocosms with L. fortunei they increased two- to tenfold. Nitrates decreased in all mesocosms. In the presence of the mussel, chlorophyll a and algal cells dropped until day 3 increasing thereafter, whereas in the controls they increased from day 0. Periphyton
growth and sediment accumulation were significantly higher in the mesocosms with mussels that in the controls. Cell density,
proportion of colonial cells and colony size of Microcystis spp. increased in all enclosures, but these increases were dramatically (and very significantly) higher in enclosures with
100 and, especially, with 300 mussels, than in the controls. Our results indicate that L. fortunei modifies nutrient concentrations and proportions, and promotes aggregation of solitary Microcystis spp. cells into colonies; both these effects can favor blooms of this often noxious cyanobacteria. 相似文献
9.
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
10.
Branka Vinterhalter Dijana Krstić Milošević Teodora Janković Jelena Milojević Dragan Vinterhalter 《Central European Journal of Biology》2012,7(4):690-697
Gentiana dinarica Beck, rare and endangered species of Balkan Dinaric alps, was in vitro propagated (micropropagated) from axillary buds of plants collected at Mt. Tara, Serbia. G. dinarica preferred MS to WPM medium, with optimal shoot multiplication on MS medium with 3% sucrose, 1.0 mg l−1 BA and 0.1 mg l−1 NAA. Rooting was not clearly separated from shoot multiplication since BA did not completely inhibit root initiation. Spontaneous
rooting on plant growth regulator-free medium occurred in some 30% of shoot explants. Rooting was stimulated mostly by decreased
mineral salt nutrition and a medium with 0.5 MS salts, 2% sucrose and 0.5–1.0 mg l−1 IBA was considered to be optimal for rooting. Rooted plantlets were successfully acclimated and further cultured in peat-based
substrate. 相似文献
11.
12.
13.
Kurtzman CP 《Antonie van Leeuwenhoek》2011,100(3):455-462
Ogataea
parapolymorpha sp. n. (NRRL YB-1982, CBS 12304, type strain), the ascosporic state of Candida
parapolymorpha, is described. The species appears homothallic, assimilates methanol as is typical of most Ogataea species and forms hat-shaped ascospores in asci that become deliquescent. O. parapolymorpha is closely related to Ogataea
angusta and Ogataea
polymorpha. The three species can be resolved from gene sequence analyses but are unresolved from fermentation and growth reactions
that are typically used for yeast identification. On the basis of multiple isolates, O. angusta is known only from California, USA, in association with Drosophila and Aulacigaster flies, O. parapolymorpha is predominantly associated with insect frass from trees in the eastern USA but O. polymorpha has been isolated from various substrates in the USA, Brazil, Spain and Costa Rica. 相似文献
14.
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
15.
Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product
formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached
to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring.
Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including
HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K
M
values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K
cat/K
M
) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to
C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan
synthase 7-DMATS from Aspergillus fumigatus. 相似文献
16.
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
17.
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
18.
A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan 相似文献
19.
Karolina Vrandecic Drazenka Jurkovic Luca Riccioni Jasenka Cosic Tomislav Duvnjak 《Mycopathologia》2010,170(1):51-60
Sunflower (Helianthus annuus) stem canker caused by Diaporthe helianthi is one of the most important sunflower diseases in Croatia. Until recently, sunflower was the only known host for D. helianthi. In our research carried out in the area of Eastern Croatia, isolates of Diaporthe/Phomospis were collected from Xanthium italicum, X. strumarium and Arctium lappa. Using morphological, cultural and molecular ITS rDNA data, isolates from these weeds were identified as D. helianthi. The following isolates were used in the pathogenicity test: one isolate originated from sunflower (Su5/04), three from X. italicum (Xa2, Xa3 and Xa5), two from X. strumarium (Xa9 and Xa12), one from Xanthium sp. (Xa13) and one from A. lappa (Ar3). According to the results, it was determined that isolate Xa5 (originated from X. italicum) was the most pathogenic to sunflower stems. The average length of the lesion was 11.3 cm. The lowest level of pathogenicity
was found in Xa9 (isolated from X. strumarium). The length of the lesion was 0.1 cm. 相似文献
20.
Zebra mussels (Dreissena polymorpha, Pallas, 1771) have had unprecedented success in colonizing European and North American waters under strongly differing temperature
regimes. Thus, the mussel is an excellent model of a species which is able to cope with increasing water temperatures expected
under global change. We study three principle scenarios for successful survival of the mussel under rising temperatures: (1)
no adaptation to future thermal conditions is needed, existing performance is great enough; (2) a shift (adaptation) towards
higher temperatures is required; or (3) a broadening of the range of tolerated temperatures (adaptation) is needed. We developed
a stochastic individual-based model which describes the demographic growth of D. polymorpha to determine which of the alternative scenarios might enable future survival. It is a day-degree model which is determined
by ambient water temperature. Daily temperatures are generated based on long-term data of the River Rhine. Predictions under
temperature conditions as recently observed for this river that are made for the phenology of reproduction, the age distribution
and the shell length distribution conform with field observations. Our simulations show that temporal patterns in the life
cycle of the mussel will be altered under rising temperatures. In all scenarios spawning started earlier in the year and the
total reproductive output of a population was dominated by the events later in the spawning period. For maximum temperatures
between 20 and 26°C no thermal adaptation of the mussel is required. No extinctions and stable age distributions over generations
were observed in scenario 2 for all maximum temperatures studied. In contrast, no population with a fixed range of tolerated
temperatures survived in scenario 3 with high maximum temperatures (28, 30, 32°C). Age distributions showed an excess of 0+ individuals
which resulted in an extinction of the population for several thermal ranges investigated.
Priority programme of the German Research Foundation—contribution 14. 相似文献