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21.
A parsimony analysis was performed on restriction sites at the Hba-ps4
pseudogene locus within one of four inversions associated with mouse t
haplotypes. The results suggest that all t haplotypes form a monophyletic
group and that the in (17)4 inversion originated before the radiation of
the Mus musculus species complex but after the divergence of the lineages
leading to M. spretus, M. abbotti, and M. hortulanus. A time frame based on
the evolutionary rate of mouse pseudogenes places the origin of this t
haplotype inversion at 1.5 Mya, or approximately 1.5 Myr after the origin
of the more proximal t complex inversion, in (17)2. The accumulated
evidence indicates that complete t haplotypes have been assembled in a
stepwise manner, with each of these inversions occurring on separate
chromosomal lineages and at different evolutionary times. In addition, the
evolutionary relationships of pseudogene sequences resulting from genetic
exchange between wild-type and t haplotype alleles were examined. Analysis
of sequences from the 5' and 3' sides of a putative site of recombination
resulted in cladograms with different topologies. The implications for
hypotheses concerning the evolutionary forces acting on t haplotypes and
their rapid propagation throughout worldwide populations of mice are
discussed.
相似文献
22.
J P Chanoine G S Stein L E Braverman V Shalhoub J B Lian C A Huber W J DeVito 《Journal of cellular biochemistry》1992,50(4):392-399
We have recently demonstrated that the iv administration of acidic fibroblast growth factor (a-FGF) to rats for 6 days results in a marked increase in thyroid weight with colloid accumulation and flat, quiescent follicular cells. Whereas a-FGF administration consistently increases thyroid weight, there are only minor alterations in serum TSH and thyroid hormones, and no change in intrathyroidal metabolism of 125I metabolism. In the present work, we studied the effects of 1 or 6 daily injections of a-FGF (60 micrograms/kg BW) or vehicle on the mRNA levels for histone, c-fos, actin, type I 5' deiodinase (5'D-I), thyroid peroxidase, and thyroglobulin and cathepsin D in the thyroid, liver and bone. Rats were sacrificed 0.5, 2, 4, 8 and 24 h after the 1st or the 6th a-FGF injection and thyroid, liver, and calvarium were removed. The relative amounts of mRNAs were determined by slot blot analysis. There was a 43% increase in thyroid weight in rats treated with a-FGF for 6 days compared to vehicle-treated rats. We observed an increase in c-fos mRNA content in the thyroid gland 0.5 to 4 h after 1 or 6 injections of a-FGF. In contrast, treatment with a-FGF for 1 or 6 days did not affect histone mRNA content, a marker of proliferative activity or actin mRNA levels. Treatment with a-FGF caused a marked decrease in thyroid 5' D-I mRNA content in the thyroid. The decrease was present 2 h after the first injection and reached a nadir 8 h later.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
23.
Claribel Cruz-García Alison E Murray Jorge LM Rodrigues Jeffrey A Gralnick Lee Ann McCue Margaret F Romine Frank E Löffler James M Tiedje 《BMC microbiology》2011,11(1):64
Background
EtrA in Shewanella oneidensis MR-1, a model organism for study of adaptation to varied redox niches, shares 73.6% and 50.8% amino acid sequence identity with the oxygen-sensing regulators Fnr in E. coli and Anr in Pseudomonas aeruginosa, respectively; however, its regulatory role of anaerobic metabolism in Shewanella spp. is complex and not well understood. 相似文献24.
Carlos G PinheiroJr Eduardo LM Naves Pierre Pino Etienne Losson Adriano O Andrade Guy Bourhis 《Biomedical engineering online》2011,10(1):31
We have now sufficient evidence that using electrical biosignals in the field of Alternative and Augmented Communication is
feasible. Additionally, they are particularly suitable in the case of people with severe motor impairment, e.g. people with
high-level spinal cord injury or with locked-up syndrome. Developing solutions for them implies that we find ways to use sensors
that fit the user's needs and limitations, which in turn impacts the specifications of the system translating the user's intentions
into commands. After devising solutions for a given user or profile, the system should be evaluated with an appropriate method,
allowing a comparison with other solutions. This paper submits a review of the way three bioelectrical signals - electromyographic,
electrooculographic and electroencephalographic - have been utilised in alternative communication with patients suffering
severe motor restrictions. It also offers a comparative study of the various methods applied to measure the performance of
AAC systems. 相似文献
25.
26.
Jill DeVito 《Oikos》2003,103(1):75-80
Safety in numbers serves as an antipredator defense strategy in many organisms, as aggregation can reduce the probability of predation for individual group members. It has long been suggested that some organisms are under selective pressure to synchronize vulnerable life stages with conspecifics, but there have been very few experimental tests of this hypothesis. Furthermore, the role of aggregation of conspecific animals within cohorts during vulnerable life stages is poorly understood.
Previous studies indicate that predation pressure may select for synchronous metamorphosis and the subsequent formation of metamorphic aggregations in North American toad species. In a series of laboratory experiments, I demonstrated that 1) Bufo americanus tadpoles in the presence of a predator exhibit higher levels of aggregation than tadpoles maintained in the absence of predator stimuli, and 2) B. americanus exposed to predator chemical cues metamorphose more synchronously than control tadpoles. I also found that toads at the climax of metamorphosis exhibit higher levels of aggregation than pre-metamorphic individuals. These results support the hypothesis that predation pressure has played a role in selection for life stage synchrony, and that aggregation serves as an antipredator defense in animals with synchronous transitions. 相似文献
Previous studies indicate that predation pressure may select for synchronous metamorphosis and the subsequent formation of metamorphic aggregations in North American toad species. In a series of laboratory experiments, I demonstrated that 1) Bufo americanus tadpoles in the presence of a predator exhibit higher levels of aggregation than tadpoles maintained in the absence of predator stimuli, and 2) B. americanus exposed to predator chemical cues metamorphose more synchronously than control tadpoles. I also found that toads at the climax of metamorphosis exhibit higher levels of aggregation than pre-metamorphic individuals. These results support the hypothesis that predation pressure has played a role in selection for life stage synchrony, and that aggregation serves as an antipredator defense in animals with synchronous transitions. 相似文献
27.
Hernández Pérez A E Cerna Chávez JC Delgado Ortiz M Beltrán Beache LM Tapia Vargas YM Ochoa Fuentes 《Phyton》2019,88(1):11-13
Mexico is the main producer, consumer and exporter
of avocado in the world, being Michoacan the main producer state
contributing more than 80% of the national production. There
are phytopathogens that decimate the production causing the
death of the tree. Root samples were collected in avocado trees
that showed the characteristic symptomatology of the disease
known as avocado sadness, the sampling was carried out in four
of the main avocado producing towns, in the state of Michoacan,
Mexico. The isolation consisted in sowing root tissue in Petri
dishes with V8®-PARPH culture medium, subsequently they were
identified morphologically and for species level it was determined
by molecular biology, with the PCR-ITS technique. Pathogenicity
tests were performed in triplicate with avocado seedlings with more
than six leaves. After 24 hours, the inoculated plants expressed
decay in the apical part, after 120 hours the leaves showed yellowing
and after 15 days there was a generalized wilt on the stem and
leaves, re-isolating the phytopathogen Phytopythium vexans.
This study confirms the first report of the oomycete P. vexans
affecting avocado trees in the most important producing region of
the Mexican Republic. 相似文献
28.
29.
Eleonore S Köhler Selvakumari Sankaranarayanan Christa J van Ginneken Paul van Dijk Jacqueline LM Vermeulen Jan M Ruijter Wouter H Lamers Elisabeth Bruder 《BMC developmental biology》2008,8(1):107
Background
Milk contains too little arginine for normal growth, but its precursors proline and glutamine are abundant; the small intestine of rodents and piglets produces arginine from proline during the suckling period; and parenterally fed premature human neonates frequently suffer from hypoargininemia. These findings raise the question whether the neonatal human small intestine also expresses the enzymes that enable the synthesis of arginine from proline and/or glutamine. Carbamoylphosphate synthetase (CPS), ornithine aminotransferase (OAT), argininosuccinate synthetase (ASS), arginase-1 (ARG1), arginase-2 (ARG2), and nitric-oxide synthase (NOS) were visualized by semiquantitative immunohistochemistry in 89 small-intestinal specimens. 相似文献30.
LM Harris L Blank RP Desai NE Welker ET Papoutsakis 《Journal of industrial microbiology & biotechnology》2001,27(5):322-328
The effect of solR inactivation on the metabolism of Clostridium acetobutylicum was examined using fermentation characterization and metabolic flux analysis. The solR-inactivated strain (SolRH) of this study had a higher rate of glucose utilization and produced higher solvent concentrations
(by 25%, 14%, and 81%, respectively, for butanol, acetone, and ethanol) compared to the wild type. Strain SolRH(pTAAD), carrying
a plasmid-encoded copy of the bifunctional alcohol/aldehyde dehydrogenase gene (aad) used in butanol production, produced even higher concentrations of solvents (by 21%, 45%, and 62%, respectively, for butanol,
acetone, and ethanol) than strain SolRH. Clarithromycin used for strain SolRH maintenance during SolRH(pTAAD) fermentations
did not alter product formation; however, tetracycline used for pTAAD maintenance resulted in 90% lower solvent production.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 322–328.
Received 12 September 2000/ Accepted in revised form 21 July 2001 相似文献