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1.
Linda E. Mayerhofer E. Conway de Macario Rong Yao Alberto J. L. Macario 《Archives of microbiology》1998,169(4):339-345
The antigenic mosaics of archaeal species are complex and lead to the distinction of different immunotypes. We began the
dissection of the antigenic mosaic of the methanogen Methanosarcina mazei S-6 by gene cloning and sequencing. The analysis of the sequence, organization, and in vitro (heterologous) and in vivo expression
of two three-gene clusters that encode proteins localized to the cell envelope and that are recognized by antibodies for surface
structures is presented in this report. The amino acid sequences and compositions share characteristics with S-layer proteins
and, most notably, have repeats of conserved sequences and secondary structures. Expressed genes produced proteins with a
tendency to oligomerize, and one of these proteins was susceptible to breakdown at regular intervals. Altogether, the data
reveal a modular system (clusters of homologous genes, proteins of similar sequences with conserved repeats) seemingly suitable
for assembling an enormous variety of final molecular structures by rearranging and combining genes, proteins, and repeats,
and thus generate the observed wide spectrum of antigenic diversity.
Received: 26 June 1997 / Accepted: 5 November 1997 相似文献
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Spontaneous Disaggregation of Methanosarcina mazei S-6 and Its Use in the Development of Genetic Techniques for Methanosarcina spp 总被引:2,自引:4,他引:2 下载免费PDF全文
Jane E. Harris 《Applied microbiology》1987,53(10):2500-2504
When monomethylamine was the growth substrate, spontaneous disaggregation of Methanosarcina mazei S-6 commenced at the mid-exponential phase and resulted in the formation of a suspension containing 108 to 109 free cells per ml. Free cells were osmotically fragile and amenable to extraction of DNA. Hypertonic media for the manipulation and regeneration of free cells into aggregates were developed, and plating efficiencies of 100% were achieved for M. mazei S-6 and LYC. Free cells of strain S-6 required MgCl2 (10 mM) for growth, whereas aggregates did not. Specific growth rates of strains S-6 and LYC were increased by MgCl2. Treatment with pronase caused sphere formation and removal of the protein wall of cells of strain S-6, but protoplasts could not be regenerated. The disaggregating enzyme produced by strain S-6 facilitated the preparation of suspensions of free cells of some strains of Methanosarcina barkeri. Although this provided a means of extracting high-molecular-weight DNA from M. barkeri, less than 0.1% of free cells were viable. 相似文献
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Defences against ammonia toxicity in tropical air-breathing fishes exposed to high concentrations of environmental ammonia: a review 总被引:2,自引:0,他引:2
Ip YK Chew SF Wilson JM Randall DJ 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2004,174(7):565-575
In the tropics, air-breathing fishes can be exposed to environmental ammonia when stranded in puddles of water during the dry season, during a stay inside a burrow, or after agricultural fertilization. At low concentrations of environmental ammonia, NH3 excretion is impeded, as in aerial exposure, leading to the accumulation of endogenous ammonia. At high concentrations of environmental ammonia, which results in a reversed NH3 partial pressure gradient (PNH3), there is retention of endogenous ammonia and uptake of exogenous ammonia. In this review, several tropical air-breathing fishes (giant mudskipper, African catfish, oriental weatherloach, swamp eel, four-eyed sleeper, abehaze and slender African lungfish), which can tolerate high environmental ammonia exposure, are used as examples to demonstrate how eight different adaptations can be involved in defence against ammonia toxicity. Four of these adaptations deal with ammonia toxicity at branchial and/or epithelial surfaces: (1) active excretion of NH4+; (2) lowering of environmental pH; (3) low NH3 permeability of epithelial surfaces; and (4) volatilization of NH3, while another four adaptations ameliorate ammonia toxicity at the cellular and subcellular levels: (5) high tolerance of ammonia at the cellular and subcellular levels; (6) reduction in ammonia production; (7) glutamine synthesis; and (8) urea synthesis. The responses of tropical air-breathing fishes to high environmental ammonia are determined apparently by behavioural adaptations and the nature of their natural environments.Communicated by I.D. Hume 相似文献
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PCR analysis of x- and y-type genes present at the complex Glu-A1 locus in durum and bread wheat 总被引:4,自引:0,他引:4
D. Lafiandra G. F. Tucci A. Pavoni T. Turchetta B. Margiotta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(2):235-240
Genes (x-type) corresponding to different high-molecular-weight glutenin subunits encoded at the Glu-A1 locus present in bread- and durum-wheat cultivars have been selectively amplified by the polymerase chain reaction (PCR).
DNA fragments corresponding to an unexpressed x-type gene were also amplified. As unexpressed y-type genes may or may not
contain an 8-kb transposon-like insertion, two different sets of primers were designed to obtain amplification of DNA fragments
corresponding to these genes. Amplified DNA fragments were also digested with restriction enzymes. The digestion patterns
of amplified fragments corresponding to unusual x-type subunits showed similarities with genes encoding the most common subunits
2* and 1. The unexpressed amplified x-type gene showed a restriction pattern similar to the one obtained with the allelic gene
encoding high-molecular-weight glutenin subunit 1; homologies were also found within the repetitive region of the linked y-type
genes. On the basis of these observations it is postulated that an ancestral active x-type gene, most likely corresponding
to subunit 1, was silenced following the insertion of the 8-kb transposon-like fragment into the linked y-type gene.
Received: 8 April 1996 / Accepted: 30 August 1996 相似文献
7.
Macario AJ Brocchieri L Shenoy AR Conway de Macario E 《Journal of molecular evolution》2006,63(1):74-86
The stress chaperone protein Hsp70 (DnaK) (abbreviated DnaK) and its co-chaperones Hsp40(DnaJ) (or DnaJ) and GrpE are universal
in bacteria and eukaryotes but occur only in some archaea clustered in the order 5′-grpE-dnaK-dnaJ-3′ in a locus termed Locus I. Three structural varieties of Locus I, termed Types I, II, and III, were identified, respectively,
in Methanosarcinales, in Thermoplasmatales and Methanothermobacter thermoautotrophicus, and in Halobacteriales. These Locus I types corresponded to three groups identified by phylogenetic trees of archaeal DnaK
proteins including the same archaeal subdivisions. These archaeal DnaK groups were not significantly interrelated, clustering
instead with DnaKs from three bacterial lineages, Methanosarcinales with Firmicutes, Thermoplasmatales and M. thermoautotrophicus with Thermotoga, and Halobacteriales with Actinobacteria, suggesting that the three archaeal types of Locus I were acquired by independent
events of lateral gene transfer. These associations, however, lacked strong bootstrap support and were sensitive to dataset
choice and tree-reconstruction method. Structural features of dnaK loci in bacteria revealed that Methanosarcinales and Firmicutes shared a similar structure, also common to most other bacterial
groups. Structural differences were observed instead in Thermotoga compared to Thermoplasmatales and M. thermoautotrophicus, and in Actinobacteria compared to Halobacteriales. It was also found that the association between the DnaK sequences from
Halobacteriales and Actinobacteria likely reflects common biases in their amino acid compositions. Although the loci structural
features and the DnaK trees suggested the possibility of lateral gene transfer between Firmicutes and Methanosarcinales, the
similarity between the archaeal and the ancestral bacterial loci favors the more parsimonious hypothesis that all archaeal
sequences originated from a unique prokaryotic ancestor.
Electronic Supplementary Material Electronic Supplementary material is available for this article at
and accessible for authorised users.
[Reviewing Editor: Dr. Stephen Freeland] 相似文献
8.
【目的】为了解猪链球菌各血清型荚膜多糖合成相关基因保守区的功能与基因进化关系,【方法】在分析已知的猪链球菌1、2、7、9型荚膜多糖合成相关基因簇序列,及其各orf与猪链球菌33个血清型基因组DNA杂交结果的基础上,提出猪链球菌荚膜多糖合成相关基因簇具有与肺炎链球菌相似的盒样结构的假设。并采用PCR、测序和Southern印迹杂交等方法验证这些假设。【结果】结果显示,猪链球菌的荚膜多糖合成相关基因簇确存在与肺炎链球菌相似的盒样结构,5’端的前4个调节相关基因同源性极高,基因簇两端都有保守的侧翼基因,且在3’端的侧翼序列中找到了适于扩增荚膜多糖合成相关基因簇中血清型特异性区域的下游引物所在基因(aroA)。分析发现,各血清型的orfY、orfX、cpsA、cpsB、cpsC、cpsD和aroA的亲缘关系较近。 相似文献
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Min-Min Jung Tae Hwan Kim Young Jae Choi Na Na Kim Ji Yong Choi 《Biological Rhythm Research》2016,47(4):583-596
The present study evaluated effects of green light emitting diode (LED) spectra on oxidative stress and circadian rhythms in goldfish exposed to various concentrations (0.25 and 0.5 mg/L) of NH3, under a white fluorescent bulb (control; simulated natural period) and green LED light. We measured mRNA expression and activity of antioxidant enzymes (superoxide dismutase and catalase) and mRNA expression of circadian rhythms (period 2), in addition to levels of plasma hydrogen peroxide, cortisol and melatonin. Damage to nuclear DNA was assessed using the comet assay. All stress indicators and melatonin were significantly lower in the green LED group than in the control group. With an increase in the concentration of ammonia, the observed effects became even more significant and generally increased with time. Comparatively, damage to the nuclear DNA was greater in the 0.5 mg/L NH3 group, and lower in the green LED group. The Period 2 mRNA expression reduced as increasing ammonia treatment but increased as green LED exposed. We have suggested that Green LED reduced levels of oxidative stress, which suggests an antioxidant effect against NH3 toxicity. Additionally, ammonia is affected the circadian rhythms and the green LED wavelength is able to regulate effectively the circadian rhythm. 相似文献
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A genetic map of the Nicotiana alata S locus that includes three pollen-expressed genes 总被引:5,自引:0,他引:5
J.-H. Li N. Nass M. Kusaba P. N. Dodds N. Treloar A. E. Clarke E. Newbigin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(6):956-964
The S locus of solanaceous plants includes separate genes that control the self-incompatibility phenotype of the pistil and of
the pollen. The gene controlling the self-incompatibility phenotype of the pistil encodes an extracellular ribonuclease, the
S-RNase. The gene(s) controlling the self-incompatibility phenotype of pollen (the pollen-S gene) has yet to be identified. As part of a long-term strategy to clone the pollen-S gene by chromosome walking, a detailed map of the region near the S locus of Nicotiana alata was generated using a total of 251 F2 plants. The map spans an interval of approximately 2.6 cM and contains five markers as well as the S-RNase gene. Two markers
were detected with heterologous probes that also detect sequences linked to the S locus of Solanum tuberosum and the homologous region of the Lycopersicon genome. Three markers were identified by differential display using N. alata pollen RNA as a template. One of these markers is a pollen-expressed sequence, 48A, which detects a polymorphic marker no more than 0.5 cM from the S locus. RNA blot analysis indicates that the 48A gene is expressed primarily during pollen development after the completion of meiosis and is therefore a candidate for the
pollen-S gene. The utility of these markers and the possible involvement of 48A in the molecular mechanism of self- incompatibility are discussed.
Received: 28 June 1999 / Accepted: 24 September 1999 相似文献
13.
Among domesticated mammals, rabbit (Oryctolagus cuniculus) is the only species possessing not more than one subclass of immunoglobulin (IgG) antibodies. The rabbit IGHGCH2 or e locus presents two serologically defined alleles, the e14 and e15 allotypes, which are correlated with amino acid variation at the IgG CH2-CH3 interface. Genetic studies, while revealing the adaptive value of this polymorphism, have relied so far entirely upon allo-antisera. Here we show how these alleles can be distinguished by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. The proposed PCR-RFLP approach allows the monitoring of IGHG locus diversity in rabbit. 相似文献
14.
Romani R Antognelli C Baldracchini F De Santis A Isani G Giovannini E Rosi G 《Chemico-biological interactions》2003,145(3):321-329
The present study looks at possible changes in the activity of acetylcholinesterase (AChE) in tissues (brain and white muscle) of the Mediterranean bony fish Sparus auratus after a 20 days exposure to sublethal concentrations (0.1 or 0.5 ppm) of copper in the marine water and on control untreated animals. The trials also included measurements of Cu concentration in the tissues to evaluate possible metal accumulation. Moreover, sedimentation analysis as well as V(max) and K(m) determination were carried out in tissue extracts of Cu-exposed or control animals. V(max) and K(m) were also determined with or without addition of Cu(2+) in the assay. No Cu accumulation occurred in brain and muscle after Cu exposure. AChE showed in both tissues a molecular polymorphism with putative globular (G) and asymmetric (A) forms. Cu exposition led to an increased specific activity and improved catalytic efficiency of AChE in brain and muscle, seemingly regarding G forms. The increase in catalytic efficiency also resulted from the in vitro assay with tissue extracts and Cu(2+) addition. The higher AChE activity and catalytic efficiency in both tissues after Cu exposition and without metal accumulation, suggests an increase of free Cu aliquot into the cells, likely due to mechanisms of metal homeostasis. 相似文献
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U6 RNA is an abundant small nuclear RNA (snRNA) required for splicing of pre-mRNAs. In mammalian cells, the genes for U1 to U4 snRNAs consist of multigene families ranging from 10 to 100 copies of real genes per haploid genome, and are transcribed by RNA polymerase II. In contrast, results obtained in this study indicate that U6 RNA, which is transcribed by RNA polymerase II and III, may be coded for in mouse cells by only two genes. These two U6 genes are at least 9 kb apart from each other, and the flanking sequences are highly conserved, indicating that the organization of U6 genes is similar to that observed for other mammalian U-snRNA genes.This investigation was supported by Grant GM 38320, awarded by the Department of Health and Human Services, United States Public Health Service. 相似文献
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We have identified and characterised a cluster of six TRIM-B30.2 genes flanking the chicken BF/BL region of the B complex. The TRIM-B30.2 proteins are a subgroup of the TRIM protein family containing the tripartite motif (TRIM), consisting of a RING domain, a B-box and a coiled coil region, and a B30.2-like domain. In humans, a cluster of seven TRIM-B30.2 genes has been characterised within the MHC on Chromosome 6p21.33. Among the six chicken TRIM-B30.2 genes two are orthologous to those of the human MHC, and two (TRIM41 and TRIM7) are orthologous to human genes located on Chromosome 5. In humans, these last two genes are adjacent to GNB2L1, a guanine nucleotide-binding protein gene, the ortholog of the chicken c12.3 gene situated in the vicinity of the TRIM-B30.2 genes. This suggests that breakpoints specific to mammals have occurred and led to the remodelling of their MHC structure. In terms of structure, like their mammalian counterparts, each chicken gene consists of five coding exons; exon 1 encodes the RING domain and the B-box, exons 2, 3 and 4 form the coiled-coil region, and the last exon represents the B30.2-like domain. Phylogenetic analysis led us to assume that this extended BF/BL region may be similar to the human extended class I region, because it contains a cluster of BG genes sharing an Ig-V like domain with the BTN genes (Henry et al. 1997a) and six TRIM-B30.2 genes containing the B30.2-like domain, shared with the TRIM-B30.2 members and the BTN genes. 相似文献
19.
Y Takada A Ito C Ninomiya T Kakizaki Y Takahata G Suzuki K Hatakeyama K Hinata H Shiba S Takayama A Isogai M Watanabe 《DNA research》2001,8(5):215-219
Self-incompatibility in Brassica species is regulated by a set of S-locus genes: SLG, SRK, and SP11/SCR. In the vicinity of the S-locus genes, several expressed genes, SLL2 and SP2/ClpP, etc., were identified in B. campestris. Arabidopsis thaliana is a self-compatible Brassica relative, and its complete genome has been sequenced. From comparison of the genomic sequences between B. campestris and A. thaliana, microsynteny between gene clusters of Arabidopsis and Brassica SLL2 regions was observed, though the S-locus genes, SLG, SRK, and SP11/SCR were not found in the region of Arabidopsis. Almost all genes predicted in this region of Arabidopsis were expressed in both vegetative and reproductive organs, suggesting that the genes in the SLL2 region might not be related to self-incompatibility. Considering the recent speculation that the S-locus genes were translocated as a single unit between Arabidopsis and Brassica, the translocation might have occurred in the region between the SLL2 and SP7 genes. 相似文献
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Increased expression of CSP and CYP genes in adult silkworm females exposed to avermectins 总被引:4,自引:0,他引:4
Ning Xuan Xia Guo Hong‐Yan Xie Qi‐Nian Lou Xing‐Bo Lu Guo‐Xia Liu Jean‐François Picimbon 《Insect Science》2015,22(2):203-219
We analyzed 20 chemosensory protein (CSP) genes of the silkworm Bombyx mori. We found a high number of retrotransposons inserted in introns. We then analyzed expression of the 20 BmorCSP genes across tissues using quantitative real‐time polymerase chain reaction (PCR). Relatively low expression levels of BmorCSPs were found in the gut and fat body tissues. We thus tested the effects of endectocyte insecticide abamectin (B1a and B1b avermectins) on BmorCSP gene expression. Quantitative real‐time PCR experiments showed that a single brief exposure to insecticide abamectin increased dramatically CSP expression not only in the antennae but in most tissues, including gut and fat body. Furthermore, our study showed coordinate expression of CSPs and metabolic cytochrome P450 enzymes in a tissue‐dependent manner in response to the insecticide. The function of CSPs remains unknown. Based on our results, we suggest a role in detecting xenobiotics that are then detoxified by cytochrome P450 anti‐xenobiotic enzymes. 相似文献