共查询到20条相似文献,搜索用时 31 毫秒
1.
Johanna Witzell Mattias Berglund Jonas Rönnberg 《International journal of biometeorology》2011,55(3):275-284
We explored the reasons underlying the biogeographic distribution patterns of the economically important, wood-rotting basidiomycete
Heterobasidion annosum in Sweden. Despite the commonness of suitable host trees, Heterobasidion annosum has not been recorded in the north of Sweden, whereas its relative, H. parviporum, is present throughout the country. To test the hypothesis that H. annosum has not spread to the north because of the effect of climate, mainly differences in the general temperature regime, we inoculated
Norway spruce stumps and standing trees with H. annosum and H. parviporum at six field sites, three in the south and three in the north of Sweden. Three strains of both species were used in random
combinations, so that each selected stump and tree was inoculated with both species at the same time. At 2 and 10 months after
the inoculations, we compared the frequencies of detection of H. annosum and H. parviporum colonies at different distances from inoculation points in the stumps and in trees. The H. annosum colonies were detected only infrequently on disks cut from the inoculated stumps (0–4% of re-isolations) in both areas, whereas
H. parviporum was detected much more frequently (26–47% of re-isolations). In standing trees, colonies belonging to H. annosum could be detected up to 210 cm (south) and 80 cm (north) and those belonging to H. parviporum up to 210 cm (south) and 140 cm (north) above the inoculation points. Our results suggest that difference in temperature
regime does not provide an explanation for the distribution limit of H. annosum. 相似文献
2.
Nina A. Lehr Aleksandra Adomas Frederick O. Asiegbu Rüdiger Hampp Mika T. Tarkka 《Applied microbiology and biotechnology》2009,85(2):347-358
The mycorrhization helper bacterium Streptomyces sp. AcH 505 inhibits Norway spruce root infection and colonisation by the root and butt rot fungus Heterobasidion annosum 005 but not by the congeneric strain Heterobasidion abietinum 331 because of higher sensitivity of H. annosum 005 towards the AcH 505-derived naphthoquinone antibiotic WS-5995 B. Differences in antibiotic sensitivity between two isolates
belonging to two species, H. annosum 005 and H. abietinum 331, were investigated by comparative gene expression analysis using macroarrays and quantitative RT-PCR after WS-5995 B,
structurally related mollisin and unrelated cycloheximide application. Treatment with 25 μM WS-5995 B for 2 h resulted in
a significant up-regulation of expression of inosine-5′-monophosphate dehydrogenase, phosphoglucomutase and GTPase genes,
while the expression of genes encoding for thioredoxin and glutathione dependent formaldehyde dehydrogenase was down-regulated
in the sensitive fungal strain. No differential expression in the tolerant strain was detected. Application of WS-5995 B at
higher concentrations over a time course experiment revealed that H. annosum 005 and H. abietinum 331 responded differently to WS-5995 B. The fungal gene expression levels depended on both the concentration of WS-5995 B
and the duration of its application. The WS-5995 B-unrelated cycloheximide caused highly specific changes in patterns of gene
expression. Our findings indicate considerable variations in response to bacterial metabolites by the isolates of the conifer
pathogen. 相似文献
3.
Holly M. Dunsworth 《Evolution》2010,3(3):353-366
The origin of the genus Homo in Africa signals the beginning of the shift from increasingly bipedal apes to primitive, large-brained, stone tool-making,
meat-eaters that traveled far and wide. This early part of the human genus is represented by three species: Homo habilis, Homo rudolfensis, and Homo erectus. H. habilis is known for retaining primitive features that link it to australopiths and for being the first stone tool makers. Little
is known about H. rudolfensis except that it had a relatively large brain and large teeth compared to H. habilis and that it overlapped in time and space with other early Homo. Our understanding of the paleobiology and evolution of the larger-brained H. erectus is enhanced due to its rich fossil record. H. erectus was the first obligate, fully committed biped, and with a body adapted for modern striding locomotion, it was also the first
in the human lineage to disperse outside of Africa. The early members of the genus Homo are the first to tip the scale from the more apish side of our evolutionary history toward the more human one. 相似文献
4.
The life cycle and developmental stages of Aylax hypecoi (Trotter, 1913, Hymenoptera: Cynipidae: Aylacini) were studied in detail. Aylax hypecoi is known to induce galls in fruits of two Hypecoum species — H. imberbe and H. geslini (Papaveraceae) and the larva develops in host plant fruits. The morphology and development of egg, larva and pupa were investigated, which
has previously not been done. The shape and size of terminal-instar larvae and associated galls are sex-specific. Overwintering
stage, adult emergence and flying periods, and egg productivity were studied also. 相似文献
5.
The research on incidence of mistletoe (Viscum album ssp. abietis) on silver fir (Abies alba) was carried out in natural fir stands in Croatia. In the area of Gorski Kotar 32.8 % of the examined dominant fir trees
were infected with mistletoe. The mistletoe incidence was presented according to the damage degrees of silver fir from 0 (healthy
trees) to 4 (dead trees), rated by the crown defoliation and needle discoloration. With the increase of incidence, mistletoe
spreads more onto more vital, i.e. less damaged trees. In the Dinaric Alps 28.6% of the examined fir trees were infected,
this percentage amounting to 27.1% for the mountainous regions between the Sava and Drava rivers.
The site and stand parameters (exposure, elevation, site quality, forest community and crown closure) were analysed in order
to establish whether there was a correlation between these parameters and mistletoe incidence. There was a negative correlation
between the elevation and mistletoe incidence. Among the compartments with a closed stands there were considerably less compartments
with higher mistletoe incidence than among compartments with a sparsely closed and understocked stands. The other analysed
site and stand parameters individually had no significant influence on mistletoe incidence.
The correlation of silver fir mortality in 2004 and mistletoe incidence in 2002/03 was analysed, and their strong correlation
was established. Mistletoe could be considered as a bioindicator of silver fir decline, and probably a significant contributor
to that decline. In the areas where mistletoe incidence is great it can be presumed that silver fir is significantly damaged. 相似文献
6.
7.
Raymond M. Harley 《Kew Bulletin》2011,66(1):171-174
A new species of Lamiaceae from Belize: Hyptis maya is described and illustrated. It is closely related to the more widespread H. lanceolata Poir., with which it is compared. 相似文献
8.
9.
Gwénaelle Crénès Corinne Moundras Marie-Véronique Demattei Yves Bigot Agnès Petit Sylvaine Renault 《Genetica》2010,138(5):509-517
The eukaryotic transposon Mos1 is a class-II transposable element that moves using a “cut-and-paste” mechanism in which the transposase is the only protein
factor required. The formation of the excision complex is well documented, but the integration step has so far received less
investigation. Like all mariner-like elements, Mos1 was thought to integrate into a TA dinucleotide without displaying any other target selection preferences. We set out to
synthesize what is currently known about Mos1 insertion sites, and to define the characteristics of Mos1 insertion sequences in vitro and in vivo. Statistical analysis can be used to identify the TA dinucleotides that are non-randomly
targeted for transposon integration. In vitro, no specific feature determining target choice other than the requirement for
a TA dinucleotide has been identified. In vivo, data were obtained from two previously reported integration hotspots: the
bacterial cat gene and the Caenorhabditis elegans rDNA locus. Analysis of these insertion sites revealed a preference for TA dinucleotides that are included in TATA or TA × TA
motifs, or located within AT-rich regions. Analysis of the physical properties of sequences obtained in vitro and in vivo
do not help to explain Mos1 integration preferences, suggesting that other characteristics must be involved in Mos1 target choice. 相似文献
10.
In the Hruby Jeseník Mts of the Czech Republic, research was carried out from 2001–2005 aimed at completing an up-to-date
census of alpine juniper [Juniperus communis subsp. alpine (Smith) Čelakovsky] and an evaluation of the overall health status of the populations, and at investigating the impacts of
the main environmental factors on the viability of this species. 13 sites were identified with 283 individuals in total, but
the sites differed dramatically in the number of recorded individuals. Comparisons with historical literature sources show
that the species has been in decline. The main reasons for this decline include: a lack of suitable sites for colonization
connected with a lack of adequate disturbance factors, competition from shading trees, and the presumed high age of the juniper
populations combined with zero generative reproduction. More than two thirds of the individuals showed slight damage to their
assimilation system. A health status of bad or very bad was determined for 5 % of the alpine juniper individuals. These trees
in the Hruby Jeseník Mts are also exposed to pressure from some herbivore insects and mammals. The populations are not yet
in a literally critical state, but considering the range of impacts affecting them, it will be necessary to pay significant
attention to their conservation strategies. Some recommendations for future management are suggested. 相似文献
11.
Marcin Sielezniew Izabela Dziekańska Anna M. Stankiewicz-Fiedurek 《Journal of Insect Conservation》2010,14(2):141-149
Phengaris (=Maculinea) arion is an endangered social parasite of Myrmica ants, and for a very long time was considered as specific to Myrmica sabuleti. Previous studies carried out in Poland suggested some discrepancies within this assumption, and therefore a much more intensive
survey was undertaken. The host ant use of P. arion was studied at five sites in different types of biotopes in Poland, i.e. xerothermal grasslands where Thymus pulegioides was used as a larval food plant by the butterfly, and more or less sandy biotopes with Thymus serpyllum. Altogether nine Myrmica species were recorded, and considerable variation in species composition and density of nests was recorded. At four localities
M. sabuleti proved to be the most common ant. A total of 529 Myrmica nests were examined, and only 20 of them contained larvae and pupae of P. arion. Host ants belonged to five different species, i.e. M. sabuleti, Myrmica scabrinodis, Myrmica schencki, Myrmica lobicornis and Myrmica hellenica. Only at one site (NE Poland) was a significant heterogeneity in parasitation rates among Myrmica species detected. M. lobicornis was the most often infested ant there, which may suggest local specialisation of the butterfly. Overall low parasitism rates
may explain the vulnerability of P. arion in Central Europe but further studies are also necessary. 相似文献
12.
Tarun Kumar Verinder Wahla Piyush Pandey R. C. Dubey D. K. Maheshwari 《World journal of microbiology & biotechnology》2009,25(2):277-285
Biological control of the cyst forming nematode Heterodera cajani was studied on sesame using plant growth promoting rhizobacteria (PGPR) Pseudomonas aeruginosa LPT3 and LPT5. Based on plant growth promoting attributes, two fluorescent pseudomonads, LPT3 and LPT5 were evaluated for
their efficacy against cyst forming nematode Heterodera cajani that parasitize Sesamum indicum. Pseudomonas aeruginosa LPT5 produced IAA, HCN, chitinase, glucanase and siderophore, and also solubilized inorganic phosphate in vitro. Moreover,
LPT5 resulted in mortality of second stage juveniles of H. cajani, which was 13% higher as compared to P. aeruginosa LPT3. Interestingly, when both strains were inoculated together for the management of H. cajani on Sesamum indicum the population of H. cajani was reduced significantly, in field trial. Approximately 60% reduction in cyst and juveniles population was recorded with
LPT5 coated seeds, while LPT3 resulted in 49% reduction in cyst and juvenile population as compared to control. Plants grown
with seeds bacterized with LPT5 and reduced doses of urea, diammonium phosphate (DAP), muriate of potash (K) and gypsum gave
maximum increase in yield, in comparison to that of plants raised under the influence of recommended or full doses of the
chemical fertilizers. Pseudomonas aeruginosa LPT5 also showed excellent root colonization. 相似文献
13.
O. V. Sirotkina A. M. Shaydina T. V. Vavilova E. I. Schwartz 《Russian Journal of Genetics》2005,41(6):683-687
Glycoprotein IIb/IIIa complex, a platelet surface fibrinogen receptor, plays a key role in producing primary hemostasis. At present, only a single mutation in the GPIIIa gene, Leu33Pro, and a single mutation in the GPIIb gene, Ile843Ser, has been described. The mutations are known to enhance signaling functions of the receptor and are associated with the development of arterial thromboses. In the present study, we describe a novel GPIIIa mutation, which is T to G nucleotide substitution in position 1585, resulting in the replacement of Leu for Arg in position 40 of the amino acid sequence of the protein.__________Translated from Genetika, Vol. 41, No. 6, 2005, pp. 838–843.Original Russian Text Copyright © 2005 by Sirotkina, Shaydina, Vavilova, Schwartz. 相似文献
14.
Maíra N. Santos Paula M. Nogueira Fernando B. S. Dias Denise Valle Luciano A. Moreira 《Transgenic research》2010,19(6):1129-1135
Vector-born diseases cause millions of deaths every year globally. Alternatives for the control of diseases such as malaria
and dengue fever are urgently needed and the use of transgenic mosquitoes that block parasite/virus is a sound strategy to
be used within control programs. However, prior to use transgenic mosquitoes as control tools, it is important to study their
fitness since different biological aspects might influence their ability to disseminate and compete with wild populations.
We previously reported the construction of four transgenic Aedes fluviatilis mosquito lines expressing a Plasmodium- blocking molecule (mutated bee venom phospholipase A2–mPLA2). Presently we studied two aspects of their fitness: body size, that has been used as a fitness-related status, and the expression
of major enzymes classes involved in the metabolism of xenobiotics, including insecticides. Body size analysis (recorded by
geometric wing morphometrics) indicated that both male and female mosquitoes were larger than the non-transgenic counterparts,
suggesting that this characteristic might have an impact on their overall fitness. By contrast, no significant difference
in the activity of enzymes related to metabolic insecticide resistance was detected in transgenic mosquitoes. The implication
on fitness advantage of these features, towards the implementation of this strategy, is further discussed. 相似文献
15.
Previous studies on the fourth inversion of the t complex, In17(4), suggest that loci near the center of this inversion have been subjected to segmental recombination during the past 1–2 million
years. We have used a combination of PCR-based restriction site (PBR) analysis and DNA sequencing to perform a high-resolution
analysis of a 2-million base pair (Mbp) segment in the middle of In17(4). We examined 21 restriction sites that are polymorphic between t haplotypes and their wild-type homologs, over nine distinct loci. In addition, we examined several other polymorphic sites
through DNA sequence analysis of two of these nine loci. We analyzed several haplotypes in this way, including the “complete”
t haplotypes t
w2
, t
0
, t
w32
, t
w71
, and t
w75
. We show that only t
w32
is a true “complete” t haplotype; the remaining four t haplotypes have segments of wild-type DNA ranging from less than 100 bp to 2 Mbp. The sizes of these wild-type DNA segments
are consistent with their being generated by gene-conversion events. The 2-Mbp segment is located in a region that may contain
the t-complex distorter gene Tcd2. One of the nine loci examined in this study is Fgd2, a gene that has been proposed to encode Tcd2. Sequencing and PBR data show that at least a portion of the Fgd2 gene has been converted to the wild-type within t
w71
and t
w75
mice. 相似文献
16.
I. Rosario G. Soro S. Déniz O. Ferrer F. Acosta D. Padilla B. Acosta 《Mycopathologia》2010,169(4):315-319
Columba livia is an important reservoir and carrier of Cryptococcus neoformans, Cryptococcus uniguttulatus, Cryptococcus laurentii and Cryptococcus albidus. Upper digestive tract of this species is also known as a habitat for Cryptococcus neoformans. Given the increasing clinical interest of this microorganism, 331 swabs from crop and 174 dropping samples from pigeon lofts
in Grand Canary Island have been studied. The obtained results show an extensive presence samples 81 positive (24.47%) of
Cryptococcus spp. in analysed crops: 32 (9.66%) for C. neoformans, 24 (7.2%) for C. uniguttulatus, 23 (6.9%) for C. albidus and 2 (0.6%) for C. laurentii. In the same way, Cryptococcus spp was also isolated in 82 (47.13%), dropping samples: C. neoformans in 59 (33.9%), C. uniguttulatus, in 9 (5.17%), C. laurentii in 8 (4.59%) and C. albidus in 6 (3.44%) of the investigated samples, respectively. The cryptococcosis produced by species of cryptococci other than C. neoformans has become more important during the last decade, supporting the study on the role of pigeon in the epidemiology of this
disease. 相似文献
17.
The intron sequence of chloroplast rpS16 and the secondary structure of its pre-mRNA were characterized for the first time in 26 Allium sativum accessions of different ecologo-geographical origins and seven related Allium species. The boundaries and main stem-loop consensus sequences were identified for all six domains of the intron. Polymorphism
was estimated for the total intron and its regions. The structural regions of the rpS16 intron proved to be heterogeneous for mutation rate and spectrum. Mutations were most abundant in domains II and IV, and
transition predominated in domains I, III, V, and VI. In addition to structural elements and motifs typical for group IIB
introns, several Allium-specific micro- and macrostructural mutations were revealed. A 290-bp deletion involving domains III and IV and part of domain
V was observed in A. altaicum, A. fistulosum, and A. schoenoprasum. Several indels and nucleotide substitutions were found to cause a deviation of the pre-mRNA secondary structure from the
consensus model of group II introns. 相似文献
18.
Previous studies have demonstrated that the obligate myrmecophytism between Macaranga ant-plants and Crematogaster plant-ants is highly species specific, although multiple Macaranga species can coexist in a microhabitat. However, the species specificity has been described based on the study of trees with
established plant-ant colonies. We studied how the process of settling into the partner Macaranga seedlings by single foundress Crematogaster queens contributes to species specificity. By sampling seedlings of three sympatric Macaranga myrmecophytes species in the field, we tested two hypotheses. The first is that foundresses correctly select their specific
partner plant species when they settle into seedlings. The second hypothesis is that the seasons in which seedlings available
for settling by foundresses appear are segregated among the Macaranga species, and the seasons in which foundress queens settle are synchronized to the appearance of seedlings of specific partner
species; thus species specificity is consequently generated. Our results support the former hypothesis but not the latter:
we always observed foundresses settling species-specific host plants, and seedlings suitable for settling were always available
in each Macaranga species.
Electronic Publication 相似文献
19.
Ying Xiao Xiaojing Yu Junfeng Chen Peng Di Wansheng Chen Lei Zhang 《Molecular biology reports》2010,37(2):987-994
In plants, stomata play a pivotal role in the regulation of gas exchange and are distributed throughout the aerial epidermis.
SDD1, a gene isolated from Arabidopsis thaliana has been demonstrated to specialize in stomatal density and distribution. In our present study, a comprehensive survey of
global gene expression performed by using an A. thaliana whole genome Affymetrix gene chip revealed SDD1 tends to be significantly lower in tetraploid Isatis indigotica than in diploid ones. To intensively investigate different SDD1 expression in response to polyploidy, a full-length cDNA
clone (IiSDD1) encoding SDD1 was isolated from the traditional Chinese medicinal herb I. indigotica cDNA library. IiSDD1 shared a high level of identity with that from A. thaliana, containing some basic features of subtilases: D, H and S regions, as well as a substrate-binding site. Real-time quantitative
PCR analysis indicated that IiSDD1 was constitutively expressed in all tested tissues, including roots, stems and leaves, both in tetraploid and diploid I. indigotica, and with the highest expression in leaves. In addition, IiSDD1 was also found to be down-regulated by signalling molecules for plant defence responses, such as abscisic acid (100 μM) and
gibberellin (100 mg/L), as well as by environmental stresses including salt, darkness, coldness and drought. Our study, for
the first time, indicates SDD1 participates not only in the defense/stress responsive pathways, but also probably involves
in plants polyploidy evolution. 相似文献
20.
Luciano Elias Oliveira Kátia G. Facure Ariovaldo A. Giaretta 《Environmental Biology of Fishes》2012,93(1):89-94
We present data on the habitat, density, and spatial distribution of Rivulus giarettai, and discuss some biotic and abiotic variables related to its abundance in Free Flowing Waters (FFW) and Dam Reservoirs (DR)
in palm grove (Mauritia flexuosa) marshes (Veredas) in Uberlandia, Minas Gerais, southeastern Brazil. The mean density (individuals/plot) of R. giarettai was about 13 times higher in FFW than in DR. In FFW, the density of R. giarettai was highest at intermediate amounts of substrate (plant mass) and it was positively rank-correlated with the depth, and the
number of arthropods. Individuals occurred in an aggregated distribution. The aggregated pattern could be related to a concentration
of individuals in microhabitats neither too much exposed nor completely saturated by plants. R. giarettai was relatively abundant and tolerant to slight man-made habitat modifications. Damming appeared to be especially problematic
by negatively affecting its density. 相似文献