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1.
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   

2.
Foraging behaviors of the piscivorous cornetfish Fistularia commersonii were observed at shallow reefs in Kuchierabu-jima Island, southern Japan. This fish foraged on two types of prey fishes: one was reef fish that typically dwell on or near substrata (e.g., Tripterygiidae and Labridae), and the other was pelagic fish that shoal in the water column (e.g., Clupeidae and Carangidae). The prey sizes, prey types and foraging behaviors changed as the predator size increased. Prey sizes were largely limited by gape size of the cornetfish, and small predators consumed small prey. The small cornetfish (10–30 cm in total length) fed only on reef fish captured after stalking (where the fish slowly approaches the prey and then suddenly attacks). The stalking was done either solitarily or in foraging association with conspecifics. Large fish (30–120 cm) fed on both types of fishes by stalking and/or chasing (where the fish chases the prey using its high mobility and attacks), either solitarily or in foraging association with con- or heterospecifics. Thus, chasing was only performed by the large cornetfish against pelagic prey fish in associative foraging with other con- and heterospecific predators. As their body sizes increased, F. commersonii began to show a diversification of foraging behaviors, which was strongly related not only to the habitat types and anti-predatory behaviors of the prey fishes but also to associative foraging with con- or heterospecifics, which improves their foraging success.  相似文献   

3.
P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

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5.
The foraging behaviour variability of three striped red mullet (Mullus surmuletus L. 1758) populations with respect to the vegetation cover was examined along the French Mediterranean coasts. We tested both the carrying capacity of different habitats and the hypothesis of a food segregation by the invasive alga Caulerpa taxifolia (Vahl) C. Agardh, on the functioning of benthic fish populations. The results indicated a significant site effect on M. surmuletus foraging behaviour and movements. The vegetation cover may play an important role in modifying the striped red mullet cost of foraging (sampling effort) and thus its strategy of prey capture. As long as the cover of marine phanerogams and/or macrophyte algae (Caulerpaceae) increases, the foraging budget and the distances covered in search of prey decrease significantly. Similarly, the striped red mullet increases the prospected sample periods to augment its foraging success, swimming above the bottom. These changes are related to the development of a dense superficial network of plagiotropic rhizomes and stolons, and to the reduction of space between fronds that limits the accessibility to resources and may increase intra-specific food competition. The role of C. taxifolia does not differ from that of other marine phanerogams but induces significant changes in the structure of Mullidae populations at the local level. The rapid expansion of Caulerpaceae in the Mediterranean Sea could constitute a real threat for the balance of the marine coastal biodiversity and the ecology of M. surmuletus, which is considered a flagship species for coastal Mediterranean demersal fisheries.  相似文献   

6.
Seol E  Jung Y  Lee J  Cho C  Kim T  Rhee Y  Lee S 《Plant cell reports》2008,27(7):1197-1206
Notocactus scopa cv. Soonjung was subjected to in planta Agrobacterium tumefaciens-mediated transformation with vacuum infiltration, pin-pricking, and a combination of the two methods. The pin-pricking combined with vacuum infiltration (20-30 cmHg for 15 min) resulted in a transformation efficiency of 67-100%, and the expression of the uidA and nptII genes was detected in transformed cactus. The established in planta transformation technique generated a transgenic cactus with higher transformation efficiency, shortened selection process, and stable gene expression via asexual reproduction. All of the results showed that the in planta transformation method utilized in the current study provided an efficient and time-saving procedure for the delivery of genes into the cactus genome, and that this technique can be applied to other asexually reproducing succulent plant species.  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.
Planktonic copepods play a major role in the fluxes of matter and energy in the marine ecosystem, provide a biological pump of carbon into the deep ocean, and play a role in determining fish recruitment. Owing to such ecological considerations, it is essential to understand the role that climate might play in the interannual variability of these organisms and the mechanisms by which it could modify the ecosystem functioning. In this study, a causal chain of meteorological, hydrological and ecological processes linked to the North Atlantic Oscillation (NAO) was identified in the Ligurian Sea, Northwestern Mediterranean. The forcing by the NAO drives most of the hydro-climatic variability during winter and early spring. Subsequently, interannual and decadal changes of the dominant copepods Centropages typicus and Temora stylifera were significantly correlated to the state of the hydro-climatic signal and tightly coupled to the NAO. Direct and indirect effects whose influence promoted phenological changes in the two copepod populations drove the species’ responses to climatic forcing. Opposite responses of the analysed species were also highlighted by these results. While years characterized by the positive phase of the NAO leads to enhancement of the strength and the forward move of the C. typicus peak, they act negatively on the annual cycle of T. stylifera, the abundance of which drops twofold and the annual peak appears delayed in time. In contrast, low NAO years lead to high abundance of T. stylifera and a forward timing of its peak, and acts in turn negatively on the C. typicus annual cycle in both abundance (low) and timing (delayed). Owing to the synchronism between hydro-climatic conditions and the NAO, and the major role of these species in the pelagic ecosystem of the studied area, these results provide key elements for interpreting and forecasting decadal changes of planktonic populations in the Ligurian Sea.  相似文献   

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11.
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   

12.
Summary   Funastrum rupicola Goyder, a new species of Apocynaceae: Asclepiadoideae from Bolivia, is described and illustrated. The conservation status of this species is assessed.  相似文献   

13.
Genome sequence analysis of Xanthomonas oryzae pv. oryzae has revealed a cluster of 12 ORFs that are closely related to the gum gene cluster of Xanthomonas campestris pv. campestris. The gum gene cluster of X. oryzae encodes proteins involved in xanthan production; however, there is little experimental evidence supporting this. In this study, biochemical analyses of xanthan produced by a defined set of X. oryzae gum mutant strains allowed us to preliminarily assign functions to most of the gum gene products: biosynthesis of the pentasaccharide repeating unit for GumD, GumM, GumH, GumK, and GumI, xanthan polymerization and transport for GumB, GumC, GumE, and GumJ, and modification of the pentasaccharide repeating unit for GumF, GumG, and GumL. In addition, we found that the exopolysaccharides are essential but not specific for the virulence of X. oryzae. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sang-Yoon Kim and Jeong-Gu Kim contributed equally to this work.  相似文献   

14.
We isolated the full-length cDNAs of engrailed and dpp-BMP2/4 orthologues from the pond snail Lymnaea stagnalis and examined their expression patterns during development by the whole mount in situ hybridization. At the gastrula and trochophore stages, engrailed is expressed in the peripheral ectoderm of the presumptive and invaginating shell gland, corroborating its role in the shell formation that is widely conserved among molluscs. At the same stages, dpp-BMP2/4 is expressed in the right-hand side ectoderm of the shell gland and in the invaginating stomodaeum. Unlike in the gastropod Patella vulgata, our results suggested that dpp-BMP2/4 has a role in the shell formation, rather than in the regional specification and that it could be involved in the specification pathway of the left–right asymmetry of the developing shell in L. stagnalis.  相似文献   

15.
Hess CM  Wang Z  Edwards SV 《Genetica》2007,129(2):217-225
We present molecular data documenting how introduction to the eastern United States and an epizootic involving a bacterial pathogen has affected the genetic diversity of house finches, a cardueline songbird. Population bottlenecks during introduction can cause loss of genetic variation and may negatively affect a population's ability to adapt to novel stressors such as disease. Although a genome-wide survey using Amplified Fragment Length Polymorphism (AFLP) markers suggests little loss of genetic diversity in introduced populations, an epizootic of bacterial Mycoplasma has nonetheless caused dramatic declines in the eastern US population. Sequence analysis of a candidate gene for pathogen resistance in the Major Histocompatibity Complex (MHC) in pre- and post-epizootic population samples reveals allele frequency shifts since introduction of the pathogen, but similar shifts are also observed in control populations not exposed to the bacteria, and in a neutral non-coding locus. Expression studies using a novel subtractive hybridization approach indicate decreased expression of the class II MHC locus upon exposure to Mycoplasma, a pattern also seen in MHC class I loci in mice infected with cytomegalovirus and consistent with manipulation of the finch immune system by Mycoplasma. These results will be further expanded using experimental studies as well as examination of evolution of the pathogen genome itself.  相似文献   

16.
Jain N  Fries BC 《Mycopathologia》2008,166(4):181-188
Microorganisms that live in fluctuating environments must constantly adapt their behavior to survive. The host constitutes an important microenvironment in opportunistic and primary fungal pathogens like Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C. gattii). In clonal populations, adaptation may be achieved through the generation of diversity. For fungi phenotype switching constitutes a mechanism that allows them to change rapidly. Both C. neoformans and C. gattii undergo phenotypic switching, which allows them to be successful pathogens and cause persistent disease. Similar to other encapsulated microbes that exhibit phenotypic variation, phenotypic switching in Cryptococcus changes the polysaccharide capsule. Most importantly, in animal models phenotypic switching affects virulence and can change the outcome of infection. Virulence changes because C. neoformans and C. gattii switch variants elicit different inflammatory responses in the host. This altered host response can also affect the response to antifungal therapy and in some cases may even promote the selection of switch variants. This review highlights the similarity and differences between phenotypic switching in C. neoformans and C. gattii, the two dominant species that cause cryptococcosis in humans.  相似文献   

17.
Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.  相似文献   

18.
Field observations and inoculation experiments revealed that Uromyces appendiculatus var. azukicola has an autoecious and macrocyclic life cycle and produces spermogonia, aecia, uredinia, and telia on Vigna angularis var. angularis and V. angularis var. nipponensis. From inoculation experiments, it was suggested that this rust fungus has different host relationships from other varieties. Morphological examinations revealed that the characteristics of urediniospores and teliospores are different among varieties, although aeciospores are morphologically similar to each other.Contribution no. 182, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan  相似文献   

19.
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   

20.
This study examines the interactions that occur between Saccharomyces cerevisiae and Oenococcus oeni strains during the process of winemaking. Various yeast/bacteria pairs were studied by applying a sequential fermentation strategy which simulated the natural winemaking process. First, four yeast strains were tested in the presence of one bacterial strain leading to the inhibition of the bacterial component. The extent of inhibition varied widely from one pair to another and closely depended on the specific yeast strain chosen. Inhibition was correlated to weak bacterial growth rather than a reduction in the bacterial malolactic activity. Three of the four yeast strains were then grown with another bacteria strain. Contrary to the first results, this led to the bacterial stimulation, thus highlighting the importance of the bacteria strain. The biochemical profile of the four yeast fermented media exhibited slight variations in ethanol, SO(2) and fatty acids produced as well as assimilable consumed nitrogen. These parameters were not the only factors responsible for the malolactic fermentation inhibition observed with the first bacteria strain. The stimulation of the second has not been reported before in such conditions and remains unexplained.  相似文献   

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