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201.
Coppoolse ER de Vroomen MJ van Gennip F Hersmus BJ van Haaren MJ 《Plant molecular biology》2005,58(5):687-698
Cre/lox recombination in vivo has become an important tool to induce chromosomal rearrangements like deletions. Using a combination of Ds transposition and Cre/lox recombination in two independent experiments on chromosomes 6 and 7 of tomato, two sets of somatic deletions up to a size of 200 kb were obtained. The efficiency of somatic deletion decreased with increasing deletion size. The largest germinally transmitted deletion had a size of only 55 kb. The results show that Cre-mediated deletion in somatic cells is less efficient when the lox sites are separated over larger distances. A further drop of the deletion efficiency after germinal transmission of the larger deletions can be explained by the probable loss of genes that are of vital importance to gametophyte function. Plasmid rescue of an 8.4 kb circularised deleted DNA showed that the Cre-mediated deletion takes place in tomato as expected. Since the circular Cre-deleted DNA could only be PCR amplified in plant cells where the deletion was not complete, the double-stranded DNA circle is assumed to be instable. 相似文献
202.
Waqar Ahmad Bushra Ijaz Khadija Shabbiri Fayyaz Ahmed Sidra Rehman 《Journal of biomedical science》2017,24(1):76
Reactive oxidative species (ROS) toxicity remains an undisputed cause and link between Alzheimer’s disease (AD) and Type-2 Diabetes Mellitus (T2DM). Patients with both AD and T2DM have damaged, oxidized DNA, RNA, protein and lipid products that can be used as possible disease progression markers. Although the oxidative stress has been anticipated as a main cause in promoting both AD and T2DM, multiple pathways could be involved in ROS production. The focus of this review is to summarize the mechanisms involved in ROS production and their possible association with AD and T2DM pathogenesis and progression. We have also highlighted the role of current treatments that can be linked with reduced oxidative stress and damage in AD and T2DM. 相似文献
203.
P450 BM3 mutant can catalyze indole to indoxyl, and indoxyl can dimerize to form indigo. But the reaction catalyzed by P450
BM3 requires NADPH, as coenzyme regeneration is very important in this system. As we know, when glucose dehydrogenase oxidizes
glucose to glucolactone, NADH or NADPH can be formed, which can contribute to NADPH regeneration in the reaction catalyzed
by P450 BM3. In this paper, a recombinant Escherichia coli BL21 (pET28a (+)-P450 BM3-gdh0310) was constructed to co-express both P450 BM3 gene and glucose dehydrogenase (GDH) gene.
To improve the expression level of P450 BM3 and GDH in E. coli and to avoid the complex and low-efficiency refolding operation in the purification procedure, the expression conditions
were optimized. Under the optimized conditions, the maximum P450 BM3 and GDH activities amounted to 8173.13 and 0.045 U/mg
protein, respectively. Then bioconversion of indole to indigo was carried out by adding indole and glucose to the culture
after improved expression level was obtained under optimized conditions, and 2.9 mM (760.6 mg/L) indigo was formed with an
initial indole concentration of 5 mM. 相似文献
204.
Differentiation of embryonic stem cell (ESC)-derived embryoid bodies (EBs) is a heterogeneous process. ESCs can differentiate
in vitro into different cell types including beating cardiomyocytes. The main aim of the present study was to develop an improved
preparation method for scanning electron microscopic study of ESC-derived cardiac bundles and to investigate the fine structural
characteristics of mouse ESCs-derived cardiomyocytes using electron microscopy. The mouse ESCs differentiation was induced
by EBs’ development through hanging drop, suspension and plating stages. Cardiomyocytes appeared in the EBs’ outgrowth as
beating clusters that grew in size and formed thick branching bundles gradually. Cardiac bundles showed cross striation even
when they were observed under an inverted microscope. They showed a positive immunostaining for cardiac troponin I and α-actinin.
Transmission and scanning electron microscopy (TEM & SEM) were used to study the structural characteristics of ESC-derived
cardiomyocytes. Three weeks after plating, differentiated EBs showed a superficial layer of compact fibrous ECM that made
detailed observation of cardiac bundles impossible. We tried several preparation methods to remove unwanted cells and fibers,
and finally we revealed the branching bundles of cardiomyocytes. In TEM study, most cardiomyocytes showed parallel arrays
of myofibrils with a mature sarcomeric organization marked by H-bands, M-lines and numerous T-tubules. Cardiomyocytes were
connected to each other by intercalated discs composed of numerous gap junctions and fascia adherences. 相似文献
205.
Marine bacteria have recently attracted attention as potentially useful candidates for the production of practical materials
from marine ecosystems, including the oceanic carbon dioxide cycle. The advantages of using marine bacteria for the biosynthesis
of poly(hydroxyalkanoate) (PHA), one of the eco-friendly bioplastics, include avoiding contamination with bacteria that lack
salt-water resistance, ability to use filtered seawater as a culture medium, and the potential for extracellular production
of PHA, all of which would contribute to large-scale industrial production of PHA. A novel marine bacterium, Vibrio sp. strain KN01, was isolated and characterized in PHA productivity using various carbon sources under aerobic and aerobic–anaerobic
marine conditions. The PHA contents of all the samples under the aerobic–anaerobic condition, especially when using soybean
oil as the sole carbon source, were enhanced by limiting the amount of dissolved oxygen. The PHA accumulated using soybean
oil as a sole carbon source under the aerobic–anaerobic condition contained 14% 3-hydroxypropionate (3HP) and 3% 5-hydroxyvalerate
(5HV) units in addition to (R)-3-hydroxybutyrate (3HB) units and had a molecular weight of 42 × 103 g/mol. The present result indicates that the activity of the beta-oxidation pathway under the aerobic–anaerobic condition
is reduced due to a reduction in the amount of dissolved oxygen. These findings have potential for use in controlling the
biosynthesis of long main-chain PHA by regulating the activity of the beta-oxidation pathway, which also could be regulated
by varying the dissolved oxygen concentration. 相似文献
206.
We examined the relationship between body size of the riparian spider Nephila clavata and the contribution of allochthonous (aquatic insects) and autochthonous (terrestrial insects) sources to its diet using
stable isotope analysis. During the study period from July to September, the body size of the females increased remarkably
(about 60-fold) but that of males remained small. The biomass of both aquatic and terrestrial insects trapped on the spider
webs increased with spider size, with the biomass of the former ranging between 30 and 70% of that of the terrestrial insects.
The average relative contribution of aquatic insects to the diet of the spiders, calculated from δ13C values, was 40–50% in spiders in the early juvenile and juvenile stages, 35% in adult males and 4% in adult females. There
was a significant negative relationship between the relative contribution of aquatic insects and body size of the female spiders.
We conclude that aquatic insects might be an important seasonal dietary subsidy for small spiders and that these allochthonous
subsidies may facilitate the growth of riparian spiders, which may in turn enable the spiders to feed on larger prey. 相似文献
207.
Linda S. M. Ooi Wing-Shan Ho Karry L. K. Ngai Li Tian Paul K. S. Chan Samuel S. M. Sun Vincent E. C. Ooi 《Journal of biosciences》2010,35(1):95-103
A mannose-binding lectin (Narcissus tazetta lectin [NTL]) with potent antiviral activity was isolated and purified from the bulbs of the Chinese daffodil Narcissus tazetta var. chinensis, using ion exchange chromatography on diethylaminoethyl (DEAE)-cellulose, affinity chromatography on mannose-agarose and
fast protein liquid chromatography (FPLC)-gel filtration on Superose 12. The purified lectin was shown to have an apparent
molecular mass of 26 kDa by gel filtration and 13 kDa by SDS-PAGE, indicating that it is probably a dimer with two identical
subunits. The cDNA-derived amino acid sequence of NTL as determined by molecular cloning also reveals that NTL protein contains
a mature polypeptide consisting of 105 amino acids and a C-terminal peptide extension. Three-dimensional modelling study demonstrated
that the NTL primary polypeptide contains three subdomains, each with a conserved mannose-binding site. It shows a high homology
of about 60%–80% similarity with the existing monocot mannose-binding lectins. NTL could significantly inhibit plaque formation
by the human respiratory syncytial virus (RSV) with an IC50 of 2.30 μg/ml and exhibit strong antiviral properties against influenza A (H1N1, H3N2, H5N1) and influenza B viruses with
IC50 values ranging from 0.20 μg/ml to 1.33 μg/ml in a dose-dependent manner. It is worth noting that the modes of antiviral action
of NTL against RSV and influenza A virus are significantly different. NTL is effective in the inhibition of RSV during the
whole viral infection cycle, but the antiviral activity of NTL is mainly expressed at the early stage of the viral cycle of
influenza A (H1N1) virus. NTL with a high selective index (SI=CC50/IC50≥141) resulting from its potent antiviral activity and low cytotoxicity demonstrates a potential for biotechnological development
as an antiviral agent. 相似文献
208.
Background
Insertions and deletions (indels) are an important evolutionary force, making the evolutionary process more efficient and flexible by copying and removing genomic fragments of various lengths instead of rediscovering them by point mutations. As a mutational process, indels are known to be more active in specific sequences (like micro-satellites) but not much is known about the more general and mechanistic effect of sequence context on the insertion and deletion susceptibility of genomic loci. 相似文献209.
A survey of blood selenium (Se) concentrations in Norwegian Red heifers and dry period cows was conducted to reveal possible
association to management, feeding, health and fertility. Selenium contents were determined in 254 herd blood samples consisting
of pooled samples from individual non-lactating animals from herds in 5 counties. The Se concentrations showed a normal distribution
with mean 0.09 μg Se/g blood, with a standard deviation (SD) of 0.05, and ranged from 0.02 to 0.23 μg/g, with 50 % of the
samples being between 0.06 and 0.11 μg/g. The herds with Se concentrations below 0.06 μg/g were smaller (21.4 ± 8.7 cow-years)
than those with Se levels above 0.11 μg/g (27.5 ± 14.1 cow-years) (P < 0.01), but there were no differences in milk yield, incidence of replacement, proportion of animal culling, amount of concentrate
or grass silage as percentage of energy consumption between the groups. Treatment registration records showed a tendency that
more animals in the low Se herds were treated for all the diseases included in this investigation (64.8 animals per 100 cow-years)
than those in the high Se herds (57.5 per 100 cow-years), while no such differences were revealed for individual disorders.
There was, however, a significant difference in bulk milk somatic cell counts (BMSCC) between low and high Se herds, their
values being 137 000 and 155 000 cells/ml, respectively. This difference was significantly influenced by herd size. Furthermore,
a total of 4 916 lactations were analyzed from individual health and fertility recordings, including 2 934 first lactations
and 1 982 later lactations. The present study revealed a reduced incidence of disease treatment with increased Se concentrations
from 0.02 to 0.23 μg Se/g blood. In this regard, there seemed to be an optimum of 0.10 to 0.15 μg Se/g for all types of mastitis
treatments summarized, and for treatment of retained placenta. Thus, herd Se concentrations below and above these values was
connected with increased probability for sum mastitis and retained placenta, reflecting the effect of the quadratic term of
Se. The cow (composite) milk somatic cell count (SCC) was lower in lactations from low Se herds than in high Se herds with
a marked SCC increase in the Se concentration interval from 0.11–0.13 μg/g blood. In conclusion, heifers and dry period cows
in Norway are low in blood Se content and there seems to be a positive association between increased blood Se concentration
pre partum and decreased incidence of mastitis, ovarian cysts and anoestrus/silent oestrus post partum. 相似文献
210.
Nishanta Rajakaruna 《The Botanical review》2018,84(1):39-78
Plants adapted to special soil types are ideal for investigating evolutionary processes, including maintenance of intraspecific variation, adaptation, reproductive isolation, ecotypic differentiation, and the tempo and mode of speciation. Common garden and reciprocal transplant approaches show that both local adaptation and phenotypic plasticity contribute to edaphic (soil-related) specialization. Edaphic specialists evolve rapidly and repeatedly in some lineages, offering opportunities to investigate parallel evolution, a process less commonly documented in plants than in animals. Adaptations to soil features are often under the control of major genes and they frequently have direct or indirect effects on genes that contribute to reproductive isolation. Both reduced competitiveness and greater susceptibility to herbivory have been documented among some edaphic specialists when grown in ‘normal’ soils, suggesting that a high physiological cost of tolerance may result in strong divergent selection across soil boundaries. Interactions with microbes, herbivores, and pollinators influence soil specialization either by directly enhancing tolerance to extremes in soil conditions or by reducing gene flow between divergent populations. Climate change may further restrict the distribution of edaphic specialists due to increased competition from other taxa or, expand their ranges, if preadaptations to drought or other abiotic stressors render them more competitive under a novel climate. 相似文献