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L. Schauser K. Handberg N. Sandal J. Stiller T. Thykjær E. Pajuelo A. Nielsen J. Stougaard 《Molecular genetics and genomics : MGG》1998,259(4):414-423
Nitrogen-fixing root nodules develop on legumes as a result of an interaction between host plants and soil bacteria collectively referred to as rhizobia. The organogenic process resulting in nodule development is triggered by the bacterial microsymbiont, but genetically controlled by the host plant genome. Using T-DNA insertion as a tool to identify novel plant genes that regulate nodule ontogeny, we have identified two putatively tagged symbiotic loci, Ljsym8 and Ljsym13, in the diploid legume Lotus japonicus. The sym8 mutants are arrested during infection by the bacteria early in the developmental process. The sym13 mutants are arrested in the final stages of infection, and ineffective nodules are formed. These two plant mutant lines were identified in progeny from 1112 primary transformants obtained after Agrobacterium tumefaciens T-DNA-mediated transformation of L. japonicus and subsequent screening for defects in the symbiosis with Mesorhizobium loti. Additional nontagged mutants arrested at different developmental stages were also identified and genetic complementation tests assigned all the mutations to 16 monogenic symbiotic loci segregating recessive mutant alleles. In the screen reported here independent symbiotic loci thus appeared with a frequency of ~1.5%, suggesting that a relatively large set of genes is required for the symbiotic interaction. 相似文献
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Thomsen PD Schauser K Bertelsen MF Vejlsted M Grøndahl C Christensen K 《Cytogenetic and genome research》2011,132(1-2):124-128
Mating of a babirusa (Babyrousa babyrussa) boar and a domestic sow (Sus scrofa) resulted in the birth of 5 live domestic pig-babirusa hybrid piglets. Chromosome analysis of one of the surviving males confirmed that they were domestic pig-babirusa hybrids by revealing the presence of a complete haploid set of 19 porcine chromosomes as well as a complete haploid set of 19 babirusa chromosomes in the karyotype. None of the surviving piglets, two males and one female, had shown signs of sexual maturity at age 27 months. Histological examination of gonadal biopsies from the 2 males revealed that both were azoospermatic. Immunostaining revealed SCP3-positive axial elements in the nuclei of primary spermatocytes, indicating that they were progressing through leptotene and zygotene of meiotic prophase. However, the presence of multiple short stretches of axial elements in pachytene nuclei indicated that this phase was blocked, probably due to aberrant chromosome pairing. Histological examination of the ovaries revealed follicular structures, but oocytes within them were generally degenerated. We conclude that both male and female pig-babirusa hybrids were infertile, most likely due to germ cell death resulting from abnormalities of chromosome pairing during meiotic prophase. 相似文献
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The small intestinal epithelium is continuously renewed through a balance between cell division and cell loss. How this balance
is achieved is uncertain. Thus, it is unknown to what extent programmed cell death (PCD) contributes to intestinal epithelial
cell loss. We have used a battery of techniques detecting the events associated with PCD in order to better understand its
role in the turnover of the intestinal epithelium, including modified double- and triple-staining techniques for simultaneously
detecting multiple markers of PCD in individual cells. Only a partial correlation between TUNEL positivity for DNA fragmentation,
c-jun phosphorylation on serine-63, positivity for activated caspase-3 and apoptotic morphology was observed. Our results
show that DNA fragmentation does not invariably correlate to activation of caspase-3. Moreover, many cells were found to activate
caspase-3 early in the process of extrusion, but did not acquire an apoptotic nuclear morphology until late during the extrusion
process. These observations show that the lack of consensus between different methods for detecting PCD may be explained both
by different timing of appearance of PCD markers and, additionally, by the occurrence of different forms of PCD during the
normal turnover of cells on small intestinal villi. 相似文献
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L. Schauser K. Handberg N. Sandal J. Stiller T. Thykj?r E. Pajuelo A. Nielsen J. Stougaard 《Molecular & general genetics : MGG》1998,259(4):414-423
Nitrogen-fixing root nodules develop on legumes as a result of an interaction between host plants and soil bacteria collectively
referred to as rhizobia. The organogenic process resulting in nodule development is triggered by the bacterial microsymbiont,
but genetically controlled by the host plant genome. Using T-DNA insertion as a tool to identify novel plant genes that regulate
nodule ontogeny, we have identified two putatively tagged symbiotic loci, Ljsym8 and Ljsym13, in the diploid legume Lotus japonicus. The sym8 mutants are arrested during infection by the bacteria early in the developmental process. The sym13 mutants are arrested in the final stages of infection, and ineffective nodules are formed. These two plant mutant lines were
identified in progeny from 1112 primary transformants obtained after Agrobacterium tumefaciens T-DNA-mediated transformation of L. japonicus and subsequent screening for defects in the symbiosis with Mesorhizobium loti. Additional nontagged mutants arrested at different developmental stages were also identified and genetic complementation
tests assigned all the mutations to 16 monogenic symbiotic loci segregating recessive mutant alleles. In the screen reported
here independent symbiotic loci thus appeared with a frequency of ∼1.5%, suggesting that a relatively large set of genes is
required for the symbiotic interaction.
Received: 12 May 1998 / Accepted: 24 June 1998 相似文献
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Torsten S Boutrup Kirsten Schauser Jørgen S Agerholm Tim K Jensen 《Acta veterinaria Scandinavica》2010,52(1):17
Background
Porcine proliferative enteropathy in pigs is caused by the obligate, intracellular bacterium Lawsonia intracellularis. In vitro studies have shown close bacterium-cell interaction followed by cellular uptake of the bacterium within 3 h post inoculation (PI). However, knowledge of the initial in vivo interaction between porcine intestinal epithelium and the bacterium is limited. The aims of the present study were to evaluate the usefulness of a ligated small intestinal loop model to study L. intracellularis infections and to obtain information on the very early L. intracellularis-enterocyte interactions. 相似文献9.
Genetic studies in Lotus japonicus and pea have identified Nin as a core symbiotic gene required for establishing symbiosis between legumes and nitrogen fixing bacteria collectively called Rhizobium. Sequencing of additional Lotus cDNAs combined with analysis of genome sequences from Arabidopsis and rice reveals that Nin homologues in all three species constitute small gene families. In total, the Arabidopsis and rice genomes encode nine and three NIN-like proteins (NLPs), respectively. We present here a bioinformatics analysis and prediction of NLP evolution. On a genome scale we show that in Arabidopsis, this family has evolved through segmental duplication rather than through tandem amplification. Alignment of all predicted NLP protein sequences shows a composition with six conserved modules. In addition, Lotus and pea NLPs contain segments that might characterize NIN proteins of legumes and be of importance for their function in symbiosis. The most conserved region in NLPs, the RWP-RK domain, has secondary structure predictions consistent with DNA binding properties. This motif is shared by several other small proteins in both Arabidopsis and rice. In rice, the RWP-RK domain sequences have diversified significantly more than in Arabidopsis. Database searches reveal that, apart from its presence in Arabidopsis and rice, the motif is also found in the algae Chlamydomonas and in the slime mold Dictyostelium discoideum. Thus, the origin of this putative DNA binding region seems to predate the fungus–plant divide.Reviewing Editor: Professor David Guttman 相似文献
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Thomas?MailundEmail author Mikkel?H?Schierup Christian?NS?Pedersen Peter?JM?Mechlenborg Jesper?N?Madsen Leif?Schauser 《BMC bioinformatics》2005,6(1):252